Well, Stormi, if I can use php semi-successfully , ANYONE can.....so it can't be THAT hard to use. I've never used vBulletin (knowingly) but if it's better than php it must be incredible. php sure gets my vote.....and it's pretty good stuff for free, IMO. What's not to like.....right ???
I think it's a matter of what you need in forum software. I personally think that forum software should have about 3 major things in mind when being built.
1. Usability - If it can't be used by -anyone- on the net, it shouldn't be here.
2. Security - the forum will not stay up for long if it's insecure. phpBB is notoriously full of holes, and constantly being exploited. That's one of the main reasons it drives me batty. It's perhaps THE most insecure forum on the net by default. Not only that but the design team believes that spam is not necessarily compromising the usage of the forums, as it -is- intended to post messages, and spam messages are still messages. Uhm,.. yeah,.. not quite a sane argument for not having security in place to stop spammers by default.
3. Modularity - making modifications to the forums shouldn't affect the entire board, or be tied to a particular theme. For instance, if we change themes ( color scheme and general layout of the board) two things will happen, 1. Error messages like crazy from several broken updates and 2. When there's an update for the software, it either can't be applied, or will have to be done manually, or #1 will happen.
The fact that phpBB meets one of three of those criteria is why I say that phpBB is cow dung. :)