CheeseDog on "Is there something wrong with public accounting?"

I've noticed a few of my professors and a number of people on this forum say something like "of course, you don't want to work in public accounting too long...." Sometimes they're referring to the Big 4 specifically, sometimes to public accounting more generally.

I've yet to work my first day as an accountant, so I'm unsure what this means. Is there some dark secret I should know about public accounting as career?