This game feels empty and will leave you wanting.
The first limitation comes in the form of a very small number of sports, there is Hockey, Basketball, Dodge ball and Volleyball, thats it. Each sport has a few different arena's which you can unlock by playing the tournament over and over, as well as some hidden characters which are mostly uninteresting.
The games themselves play well, the controls are good and let you play like a pro with minimal fuss, but if you were looking for complex and deep controls again look elsewhere because the game does most of the thinking for you. For the most part it will automatically perform the required action when you are in a certain position and press a certain button, for example - in volleyball to do a slam you just have to be near the net when the ball is coming to you and press jump and you will do one.
You chan choose only 2vs2 or 3vs3 matches, up to 4 players, which given that the arenas are quite small seems like enough but ultimately feels lacking. You wont be able to make your dream team here, just take a couple characters along for the ride. While this may seem OK it really make each match feel like a drawn out min-game then an actual match.
The tournament is very stripped down, 8 teams face off and you move up the tree by winning, here you can unlock more arenas and characters but as the games are so shallow this gets very repetitive very fast and youll find yourself not wanting to play the tournaments more the once. Each sport does have the usual "mario cups" (mushroom, flour, star) each has different arena's but offers little in the ways of added challenge.
The arenas themselves are nice, they offer some variety as in many you will have different obstacles or bonuses but there arent very many of them and they are fairly similar for each sport so even this does little to prolong the games longevity.
The game can be fun for a round or two with friends but again it looses its charm quickly, there is also a "party mode" in which you basically run to your color and as Im sure you can imagine this looses its appeal rather fast.
They could have really done alot more with this game, the core mechanics are good and could have had potential if the game had a little more depth, even a story mode for each sport would have really added to the experience. Also a couple more sports wouldnt have hurt either and would have made the games title a little more appropriate as currently I dont think you could call it a "mix".
If your looking for a simple sports game to play with your favorite nintendo characters then you may enjoy this but if your looking for any real substance or depth you will be disappointed. This might be a good buy at $20 but I wouldnt pay full retail as this game is more akin to $15 down-loadable games on PSN or XBL then it is to a full priced retail game.