It's an okay book, but the LSAT Explained book is better, plus it covers newer LSATs. Either one you use, they are the only books that explain real LSATs. They have a newer games book called Ace the Logic Games, I am waiting for it to arrive. From what I saw online it looks really good.
Can you keep up the hard work for another 4 months? If you can, then I don't see what you shouldn't imrprove to where you need to be. Take all the prep tests, then take them all again. If that doesn't get you a 170, nothing will.