I've been staff in a fair few places - mostly smaller forums, although I've moderated a couple of larger ones too. In those places where I have been staff, I've enjoyed being able to more easily get ideas I've had for site events etc. off the ground...fundamentally there isn't much difference between being a staff member and just a regular member, but I've found that being staff in places DOES make it easier to get people to participate in things, since it's "official" or whatever. Also, little pride creeping in, but...well, on the roleplaying forums I was a mod on, being recognised for my writing ability that way was nice.
I guess the things I disliked were due mostly to my own temperament. I always worried that I was a dead weight and that I wasn't doing enough on the forum, that other members of staff hated me, and because even when I'm part of a group I'm an outsider - I don't really talk to people, and I'm not really approachable either I guess, so I'm just kinda left alone to run my own section, completely isolated from everyone else. So I did a lot of worrying. Feeling like I'm being held accountable for things I am doing voluntarily because I enjoy them has never been a nice feeling for me, because I immediately stop having fun and start worrying about whether I'm doing it "right" or not, and of course, I am always doing things wrong.
So yeah. Being a mod is always nice, but finding out that I may not have the right state of mind - and trying to force myself into what I believe it may be, even though logically I know that's ridiculous - to be a mod is not.