Still Holding up like it did for GC
It is almost the exact same as Mario Power Tennis GC. It has the same tournaments, same characters, same abilities and same graphics. You will hardly believe this game was made in 2004. It still has very good graphics besides some of the crowd. You can tell Nintendo made this game, but it's graphics still look great for Wii and you won't notice the fact that this game was made 5 years ago.
Although the controls are the main change, the gameplay has changed slightly. It is a lot like Wii sports, but you can't just wildly swing. You have too have to hit the ball at the right time. It will not be any problems hitting the ball and sensitivity issues will not cost you the match and will rarely happen. Also every swing you do there will have a certain spin and certain speed. If you swing early and late it will be a weaker hit and if you swing forehand instead of backhand it will likely go out, but sometimes it won't be to badly effected. In the GC Mario Power Tennis it was hit it until the opponent misses. On Wii if you hit it hard and the opponents on the run they sometimes mess up. Player movement will be easy by just using the Nunchuk. The characters are evenly balanced in skill, but you will find your own favorite.
It is obvious Nintendo didn't need any noticeable changes other then controls to make Mario Power Tennis still a great game. The engine holds up well and the new controls are a great new idea. What I gave Mario Power Tennis GC, a 9.5/10.