I'm gonna agree there (@powerhouse)... Just playtested MK. It's hard to say for sure as none of us have really used or faced MK much before (believe it or not, I know almost no one who used him... even in vBrawl), but our first impressions were that he was, at the very least, an extremely easy character to do pretty well with. It's hard for me to say for sure if he's overpowered overall though atm... I just don't know the MK's matchups that well yet. (at first, for example, I thought Bowser destroyed MK... then I started throwing Bowser off stage and the match seemed closer to even despite MK having so few moves that break his armor)
I will say though, it seems like shuttle loop is an extremely high reward move for almost zero risk... maybe my friends just aren't used to facing MK (it was me primarily that was using him), but it seemed like at the very worst I would hit the opponent a good distance away and I would get nicked, meaning I could go for it again before landing...
That said, I'm fine with him being the best gimping character in the game if that's his thing (so in other words, I'd rather him keep the "high reward" bit and maybe just make it slightly more punishable/ maybe lowish priority)... but presently he also has the whole "most of my attacks are hard to punish and do pretty decent damage and come out instantly" thing going for him as well, so if he's too much... nerf one of those things. Not sure he needs it and I might change my mind there, but that's how I feel so far.
Again, I really haven't played MK much aside from last night, so take it with a grain of salt... but that was my first impression.