The playable character roster did not live up to the expectations set to it, and most fans have voiced disappointment over it. Personally, I've long since decided I'm happy with it, with only three real lasting complaints, even though it didn't meet my previous expectations either.
I haven't actually played the game, but the above aside, everything looks fantastic. The soundtrack is amazing (and massive - Brawl has a little over 1 gig worth of space spent on music alone). The stages are almost all wonderful (though I've seen some fans say they were disappointed at the selection of past stages and the lack of a couple of hoped-for new ones), and I've already seen some stage-creator made ones I love as well. Subspace Emissary I've avoided spoilers for as much as possible, but the couple of scenes I did see looked just as great as what the Dojo showed before (and even much better, in a few cases). For competitive players, I've heard some are already hard at work coming up with new advanced techniques/abuses to use (haven't followed it specifically, since I'm a casual player myself, but I've perused a couple of threads about the subject). The combat videos I've seen look just as exciting as ever - slowed down a bit and with more airborne combat due to characters floating longer, but just as exciting nonetheless.
So yeah, roster aside (and I've learned to like that too), its pretty much as good as or better than expected for me. Your mileage may vary, of course.
Zevox