I thought it was just mediocre as well. Great animation, great set and character design.
However, the story was not very fun or interesting (not to mention 100% predictable) -- by the end, it somehow seemed like it both dragged and was cut too short. Doesn't it seem like it ended rather abruptly?
Also, I usually like Danny Elfman (I LOVED his stuff for Charlie and the Chocolate Factory) but the songs in this one were el stinko. The opening sequence was especially dull.
If you're a huge Burton fan you'll be seeing it anyway, but for the rest of y'all... stick it on your Netflix list.