Aspartame what say you?

Okay so here is something that is throwing me for a loop, What do you know about aspartame? I did a search on Web M.D.and saw both sides, it is bad, it is not bad! So which one is it? My kids like the drinks that have aspartame in them, like Fresca, and the flavored waters. But I have heard it is bad. So what do you know about that, and besides web M.D. is there somewhere else to check on something like that?