Keep a copy of the core book next to you if possible, so you can make sure (the GM) he's playing by the book. If he is not, let everyone in the room know this and demand that he not short-change you.
Any GM who can not be bothered to learn, work within, and use the rules he paid nearly $40 US for, that everyone else most likely paid $40 US for as well, and who are fully expected to abide by said rules, should not be in the GM's chair.
Contrary to popular belief, a GM really should be 100% impartial, work within the rules, and rarely (if ever) use Rule #0, which was originally designed as a way to handle things rules do not cover clearly, not as liscense to be a complete and total dick to your players or to do whatever you damn well please and throw 'Rool 0' at players when they ask why everything they do 'mysteriously fails' or whatever other inane explanation the GM gives to help rail-road a plot along.
Honestly? I have to agree.