Very fun gameplay,easy controls, good customization,great graphics, and a good selection of characters...only problem is rarely anybody is online and the gameplay can get competietive at times also there are not character specific special moves.
I love Tennis, and I'm a Mario fan, so this was good for me. Is it good for you? I don't know, that's your call. I can tell you what is good about it. Easy gameplay mechanics, the ability to play as your Mii, able to dress your Mii, etc. Just try it, I recommend it.