Just as a quick follow-up to that, for anyone wishing to play a wizard, I guess the most important thing to remember is that magic itself is not a completely understood aspect of the world. Your character can't possibly know everything there is to know, and failure is bound to happen, just like a warrior's sword is bound to miss. I want the world to feel dangerous - if someone breaks a leg, then they may be out of commission entirely, because a wizard's spells aren't going to be able to mend that. If a group finds themselves lost in a tundra, then that's going to be detrimental to their journey, because the wizard isn't going to be able to just summon up some better temperatures whenever someone feels a little cold.

I totally encourage anyone who wants to take on a magic-user, but I also don't want that character to become the be-all-end-all, as I've seen far too often in other roleplays I've been a part of.