So I've spent like 10 hours on the demo now D: to be fair, at least 5 of those were on multiplayer mode with my gf and/or my brother, so it's not been all AI-battling, but wow. I think I have like 8000+ coins collected too.
I really like Pikachu and Villager. Villager's tree mindgames are insanely fun, something that one can't really appreciate playing against the AI (my brother now hates me), and Pikachu... I don't think I've ever played him for long except maybe in SSB 64, but I really enjoy some of his moves, specially those that do multiple hits like his back-air and down smash, and he's really quick.