IIRC, I signed up with my Hotmail account. But that was a little over a year ago, so things have probably changed.
As for whether or not its worth its to get another email address to sign up, that's entirely up to you. I personally enjoy PBF but I'll admit its not for everyone. I remember lots of discussions on Whiteblaze about how PBF would never make it and how it is run as a dictatorship. If that's how you feel there are plenty of other forums that are probably more to your liking. No one is forcing you to participate on PBF, here, or any other forum. If you go in with an open mind, knowing that PBF is a little different than you are used to, you will probably enjoy PBF, just as many others do.