Tim Burton has made some astounding pieces of work, and some that do not live up to that legacy. I haven't seen anything of his that was horrible (haven't seen Alice yet). Charlie and the Choc Factory was the weakest I've seen so far; by no means a terrible movie, there was nothing to really recommend it either. It was a movie, something on which one could spend some time, but it wasn't particularily special, and he could have done better.
If you think Tim Burton is overrated, then I pretty much have to conclude that you're not being fair. Compare him to the greats, he may not blow them off the stage, but he certainly belongs in that kind of company.
What I don't get is why everything either has to be "the best" or "omg fail". Can't people just sit down and watch a frikkin movie anymore, without it having to be the best they've seen so far or a complete waste of their time? If the worst waste of time you've ever been guilty of was watching Alice, then I'm pretty much going to have to applaud you, for you have lived a truly blessed life. As for the rest of us, you could do a helluva lot worse with an evening than watching ANY Tim Burton movie.