Must admit i never was overly exited for Little Mac, likely because i never played Punch Out, dislike sports in general and think his design is pretty bland (things that still apply).
I do admit that his preview video makes him look like a character i'd like to try out, though. He obviously has some moves that rely on what would be called "invincibility frames" in a normal 2D fighter, which gives me the hope that his gameplay style will make a connection between SSB and "real" 2D fighters. Might seem a bit stretched judging from the few things we have seen, but he is a martial artist, after all.