James Heisig deployed an elaborate mnemonic system to help learn the meaning and writing of the kanji in Remembering the Kanji I, and many people will come to the second book expecting something similar for the readings. Unfortunately, Heisig has run out of magic for this task, and all he has to offer is brute-force memorization like everyone else. Remembering the Kanji II is basically nothing but an abridged dictionary of kanji readings, and you are expected to just drill through it without any special tricks.
I found the first book very useful but this one just dry and demotivating. There is little to be gained from learning kanji readings using RTK2; I found it much better to just start reading Japanese texts and look up the readings as I went along.
The only advantage RTK2 really gives you is that it teaches you readings corresponding to primitives. So you can save time by learning, say, a block of 5 kanji with the same sound-determining primitive all at once. But this only works for a few hundred kanji, and is something you'd be naturally be doing anyway even if you learned readings ad hoc. So you might find RTK2 somewhat useful, but if you don't buy this book you really aren't missing out on much.