I looks great! I liked Mario Tennis 64 a lot, but it's the type of game I binge on every year or so and then quickly get tired of. From the looks of these screenshots, Mario Tennis GC has more modes of gameplay, but I still can't see myself shelling out 50 bucks for it. Maybe if the controls are vastly improved, it'll wow me. Mario Tennis 64's controls were fun, but also a little frustrating.
This game seems to be a LOT more than just tennis. It's like that one Bowser tennis board, only about a whole lot more. This is what Mario is intended to do to sports, toss in lots of things never intended for the game to really make it fun!
"On two occasions, I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question." ~ Charles Babbage (1791-1871)
Of course it'll be better than that, it's the entire focus of the game. And any tennis game that lets you use a giant hammer instead of a racket is awesome in my book. :)