Oh, right, the SSE. Personally, I thought it was sort of a disappointment. I thought that the idea of putting the Smash Bros. characters in a platformer would play out really well, but somehow it got redundant very fast -- due in part, I'm guessing, to the fact that not that much changes from stage to stage besides what the scenery looks like. If, in future SSB installments, they would bring in some people from a different department who specialize in making platformers, that would make whatever Adventure Mode they aspire to a lot better.
Oh, and the bosses. I thought they were cool but a little too tough to faze. To me, Super Smash Bros. is a game where if you hit people, they recoil. I wasn't crazy about the bosses following easily discernible patterns of movement and then just floating there waiting for you to hit them (and not moving when you do.) I can understand this for certain bosses like Tabuu or the classic examples of Master and Crazy Hand, but how Ridley takes a solid kick to the chest without budging is beyond me.