The controls and graphics are ABYSMAL.
for starters, it is INCREDIBLY awkward trying to do regular moves, tripping is awful, a ton of final smashes suck, many(and I mean MANY)of the stages are just ATROCIOUS, many "special" things like Zelda turning into Sheik, Snake's call codecs, and so on are WAY too complicated to figure out. The graphics try to look dark and gritty, but end up dirty and ugly af; I know that's how Wii graphics usually look, but it's ugly even WITH that in mind. Easily the worst of the smash games imo