I question full-on veganism for the simple reason that most vegans are so damn full of themselves. I mean, no offense to any vegans who may be reading this at the moment - I'm sure you're fine - but I went to a college that had a LOT of vegans, and while some of them - a number of them, actually, to be fair - were perfectly nice, normal people, the ones who were serious about it were SERIOUS about it. I got nagged about my eating habits on several different occasions, and actually had one guy try to convert me to veganism through persuasive argument over the course of something like TWO WEEKS. Every time I sat down to eat lunch in the cafeteria, this guy would come over and start preaching at me. It's like the liberal arts version of Jehovah's Witnesses.
Oh - and their pies suck.