PLS is one extreme of the law school book "spectrum". There's also the other extreme--skinny little books that give you essentially no information that is of any use whatsoever and lull you into a false sense of security. PLS freaked me out when I first started reading it because I thought there was no way I'd be able to succeed in law school if it's really this bad. But I don't think it will be. The most valuable part was the timetables of things to read/study to prepare for law school. I'm not going to be able to do all of the stuff, but I'm doing some of it so that I can have a head start. Couldn't hurt, anyway.
I don't think studying a few hours a day will exactly burn me out when I have 4 months of complete free time. I'll be screwing around 80% of the time and studying maybe 20%; sounds relaxing to me. Plus I'll have a big edge on all my fellow classmates.