Hoo boy, where do I even begin...
let's see, oh yes. Clones. When you have stat modifiers, alternate moves and the wasted potential of alternate costumes, there really isn't any justification in my opinion of adding clones. F****** Dark Pit, his only discernable visual difference from Pit, designwise, are his colours, that's it.
And on the subject of costumes, so much wasted potential. No proper Medusa colours for Palutena, No shiny Charizard, Sonic's are still as awful as ever (I love using Sonic, but something's wrong when I think deviantart does a better selection of colours for Sonic than Sakurai). And then there's the actual alternate costumes, why does Project M do a better job with them than Sora/Namco?
The roster, I'm sorry but not a single newcomer has really attracted me, a few look interesting to play as but I've never been excited over any of them.
Dr. Mario. Why does Sakurai insist on keeping FLUDD for regular Mario? Why couldn't they have simply made the Doctor a costume and the Tornado an alternate move? Seriously, his Final Smash is just a reskin of Mario's.
No Ridley or Mewtwo hurts, and the cuts from the roster are the worst yet, no Wolf (I love him in Brawl), no Lucas, no Ice Climbers (the worst of the cuts)
The Final Smashes. Sonic got nerfed badly, Giga Bowser and Donkey Konga are as useless as ever. Why the F*** does Falco still have the landmaster!? So many chances to change things up, improve on stuff, but noooo we can't have any of that now, can we!?
The Stage selection sickens me, five Mario stages (and one of them is the awful mushroomy kingdom), and bad retro stages instead of new ones for some franchises.
Both the CSS and the SSS are a mess, clone corner? What's stopping them from being with their respective franchises? (as much as I dislike clones, I still feel it shouldn't have been arranged this way on the CSS)
No target test is disappointing, would have added some more replay value. (plus I want the targets theme from Melee to return, it's the best track in the entire series)
There's probably more but that's all I can think of at the top of my head.