Although armlocks (and other jointlocks) were a major part of jujutsu, for some reason the armlock is more widely studied and used by western judoka (I have read statistical accounts of this). Perhaps the reason is because it strikes Westerners as "dirty" to choke someone, whereas it is considered efficient in Japan. Also, at least traditionally, the Japanese considered it disgraceful to submit in contest so an armlocker would be forced to actually dislocate the armlockee's elbow to win. However, with choking the failure to submit will only result in unconsciousness. So maybe chokes and holddowns were practiced and used more by the Japanese so that no one had to get hurt in order to uphold their honor. Another consideration may be that while true armlocks are not allowed in any extant style of western wrestling (that I am aware of--SAMBO excepted but it is based mainly on Judo anyway) yet many wrestling techniques work against the shoulders and arms to maneuver the person for a pin in a ways that have some relation to jointlocking (i.e., the hammerlock). The book starts off with a little history of Judo and discusses how Russian SAMBOists revolutionized the application of juji-gatame (Adams only says "armlocks" but I think he means to say juji-gatame which is the most common armlock and the only one that I know of which the Russians put their stamp on). Adams himself was inspired to specialize in juji-gatame after seeing the Russian Yaskevich use it. One common misconception, however, is that he Russians invented juji-gatame which is inaccurate-they simply developed it more, probably for the reasons I mention above and the fact that SAMBO does not allow choking. Adams, however, is apparently less inspired by the other SAMBO skills imported into judo such as the unorthodox throwing and gripping methods which he criticizes a bit in this book and other books I have read by him.
The first chapter starts off with juji-gatame as is fitting because it is the most popular competition armlock. The reason is not hard to figure out. Tori is able to use his legs to control uke's body and then use the power in his arms, back, and hips to force uke's now isolated arm straight. Also, it is capable of being applied in a wide variety of situations and uke is well controlled so that tori has some time to force the lock on-unlike, say, a lot of standing locks.
Adams starts off by showing the classical and modern forms of juji-gatame. The classical form is where only one leg is across uke's head and the other is wedged up on uke's near side. The modern form has the second leg across uke's chest-this offers significantly more control. The classical form is seen a lot less often, but is used occasionally when the lock is applied in the transition from throw to groundwork (it is then too awkward to get both feet over to the other side). He then shows two finishing positions: juji-gatame applied while trapping uke in a triangle choke (often called sangaku-gatame) and what Adams calls a "Pillow juji-gatame" where the chest and head is scissored from the side and tori pulls uke's arm down towards uke's feet instead of back.
One other move is shown here which is kesa-gatame (scarf hold-a kind of side headlock pin) into juji-gatame. You can go into a regular juji-gatame but Adams shows a slightly different variation where the arm is pulled over your thigh and held under your own armpit as opposed to the normal way of pulling the arm between your legs with the hand held tight to the chest. Nothing wrong with that but Adams doesn't really explain the difference and you can't see it in the photograph that well (I only recognized it because there is a similar move shown in A-Z of Judo from kami-shiho-gatame). Adams claims that it is a good move if you don't think you can hold the pin for the full 30 seconds. Unfortunately, this is the only time he demonstrates a juji-gatame from what would otherwise be osaekomi-no juji-gatame from the mount for BJJ fans. But this is a book about sport judo. Next is a photo sequence of the flying juji-gatame attack from standing used by many Russian players. This is like jumping off the top rope in Pro Wrestling-"a high risk maneuver." If your back hits the mat hard enough and you don't get the other guy flying you may well be called for ippon. At the other extreme, your opponent's arm can break pretty easily if he doesn't react quick enough and go with it. Anyway, you'll probably have trouble finding training partners to let you practice this move.
Adams then demonstrates 8 juji-gatame attacks from the back mount (which he calls "Turns"). These are all really good, the only problem being that both Adams and his partner are wearing white gis which makes it hard sometimes to see what is going on. In all of these he ends up in the modern two leg style juji-gatame except one where he is in the triangle choke. One thing I was surprised at is that he doesn't show using the threat of a choke to start off some of the turns and that he doesn't demonstrate starting the turns as your opponent fails at a throw. This is really simple: guy turns in for drop seoi-nage, block it and pull him back with your lapel grip and lay onto your back a little off to the side and bring your leg up over onto his head and, viola… Adams then demonstrates 4 juji-gatame attacks from the guard (which he calls "Spins"). All of these are good too but I feel the first two techniques were a little incomplete. The first one is called "Head Control." As I see it, there are two variations on this. One, which is more similar to what Adams shows, is where the guy has his head low in your guard but with his arm across his body. You swing over towards the other side arm and lay your leg over the back of his head. This is the one the Gracies use a lot and normally the person in the guard is still on his knees when the hurting starts (Royce v. Hackney). This is most of what Adams shows except his uke goes over onto his back. The second is where uke has his head sticking up and you just hook it with your leg and pin him back to the floor and straighten the arm.
The second spin is where Adams pivots under his uke and then rolls inwards and winds his uke to the floor over the top of him (with the aid of a grip on his leg). However, there is another common variation where tori pivots under but then straightens back out and ends up in the lock often with uke still on his knees.
The other two spins show the triangle choke variation and a face down juji-gatame where you kick uke's one knee out from under him and slide away onto your stomach applying the lock. Adams then moves onto a chapter on finishing juji-gatame. This chapter is really great except for that white on white problem. He basically shows you a bunch of tricks to straighten the arm. He also discusses crossing your feet and trapping the far arm. This takes the power out of uke's back muscles by pulling his arms in together. One problem he doesn't mention though is the dangers of crossing your feet without trapping the far arm. Like I said, I love all the tricks but two that he doesn't show: reaching down and putting a one hand lapel choke on a stubborn uke and kicking (well, using foot pressure) against the bicep of uke's far arm if he is using it to hold his other arm in. There are also a bunch of wristlock type tricks you can use but these are vaguely illegal so we wouldn't expect them here.
Despite my criticisms, I would give the stuff so far a 5-star rating. It gets a bit weaker as we go on. The next chapters deal with a variety of other armlocks. The chapters on ude-gatame (straight armlock) and ude-garami (arm entanglement or figure four type lock) are pretty good. He shows some of these from the guard and, surprisingly, some from osaekomi. I would think that he would at least show them against a half-guard (one leg trapped) type of position. For a judoka, these would be the most relevant applications but you can probably figure the stuff out for yourself. Also, he shows using ude-garami as a sweep from the guard into osaekomi and ude-garami combined with a triangle choke.
Then there are three short chapters. First, waki-gatame (armpit lock--on the ground). Adams only shows one variation but it is pretty slick: a sit out reversal from the turtle position where your opponent is holding from the front. But that is it. Then he shows some standing armlocks but these are mainly "demonstrated" by competition photographs and there is not really any explanation of the situations or grips which give rise to these combinations nor using them in combination with throwing attacks. Of course, standing armlocks are mainly used to break stubborn grips but I felt this chapter somewhat incomplete. Finally he shows hara-gatame (stomach lock--sometimes called ashi-gatame). I like the combination Adams shows (hara-gatame into kata-gatame). But again, that's it. The last chapter is on "special combination." This should be the really good stuff but it is kind of flat. First he shows sitting up from juji-gatame onto the person for an osaekomi in a kind of straddle mount. British judoka Neil Eckersley used this a lot and it bore his name for a while. However, this move recently been classified by the IJF under the title "uki-gatame" (floating hold). The classical variation of uki-gatame is the knee-on-chest position you seen in BJJ. Personally, I don't like the fact that this is an osaekomi because I think the position doesn't provide tori with much tactical advantage if it were a real fight, but I don't make the rules. Better combinations which Adams shows, IMHO, are coming out of a juji-gatame into tate-shiho-gatame or kami-shiho-gatame. Then we have two uses of the triangle choke to counter an opponent who is trying to get out of juji-gatame-these are good. And finally, just one standing to groundwork combination in juji-gatame applied using a failed or faked tomoe-nage set-up.
One problem with the book is that while all the stuff shown is good it doesn't really tie everything together. There is no section on defending or countering the various armlocks; consequently, except for the two triangle chokes mentioned above no mention of how to counter any escapes or counters. Throughout the book Adams's uke is like a passive dummy. There is no demonstrations of using certain armlocks to counter certain types of ground attacks or attempts to pass the guard. Overall, there is no sense of using armlocks as part of an integrated strategy along with chokes (except the triangle which is apparently the only choke that Adams used) and only a few holding and throwing combinations are shown (tomoe-nage as above and tai-otoshi is shown in the competition photos). For these reasons, it gets the 4 stars instead of 5.
There is a short self-defense section. Adams shows a kind of standing waki-gatame armbar from a lapel grab and a basic kote-gaeshi wristlock. Then he shows a wrist grab escape. You can pretty much tell that his heart is not in it. He doesn't think judo should really deal with self-defense (he doesn't say this here but I have read it elsewhere). As usual, the book ends with some competition photos.