First, the Kalashnikov (1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 e5) is actually an accelerated Sveshnikov (1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 e5) making them close relatives.
This line (4...e5) is also sometimes known as the Neo-Sveshnikov. The move 4...e5 is not new. La Bourdonnais used it in matches against McDonnell back in 1834 and it was briefly popular in the 1940's. But in the late 1980's 4...e5 was revived with the intention of meeting 5.Nb5 with 5...d6: this is the Kalashnikov Variation.
Black accepts a backward pawn on d6 and weakens the d5-square but gains time by chasing the knight. The difference between playing 4..e5 and delaying it a move is that both sides have extra options since neither side has developed their N: white on c3 and black on f6.
One advantage for black is that the variation is fairly easy to learn. Another is that the defense has clear strategic aims. Yet another advantage is that it can be used by both tacticians and positional players because black can chose between aggressive and positional options.
Another good thing about this book is, it answers the question, “What if white plays something else?” Like, say, the Rossolimo, Alapin, Closed, Grand Prix. Rotella also covers lines against those, obviously not as extensively, but well enough o get you by.
OK, so Rotella is untitled. It's still a very good book that will be useful for players rated from 1600 to 2200 that are looking for a good line in the Sicilian.