The numerous control methods convolute what is an otherwise simple and sparse tennis game. That simplicity extends to the courts, which are themed, but differ only in court surface--at least until you reach the final tournament and the Galaxy Court. The Galaxy Court has cycling surfaces, which can be triggered by landing a smash on your opponent's side. Mostly these are just clay, sand, grass, and so on, but one surface takes the form of a black hole, which sends shots bouncing wildly off course. It's an odd inclusion, as it's the only unrealistic court gimmick, and isn't included anywhere else in the game.
You can play through singles or doubles tournaments in single-player, breezing through until the final difficulty spike. Doubles tournaments don't work quite as well as singles by yourself, since your AI companion will occasionally forget how to play tennis, diving into the middle of your rallies, choosing not to hit the ball, or simply failing to perform the majority of chance shots. The entire single-player campaign is somewhat dull, though, and quickly sees you going through the motions purely to complete things.
Luckily, there's multiplayer on offer, both local and online. Local play also has download play enabled, which is a welcome addition. It's the same tennis mechanic, but playing with friends offers more than taking on the rigid AI. If you play online versus random opponents, you can only play singles matches, and then only brief knockabouts with low set counts; the ideal way to play Mario Tennis Open is with a group of mates. There's also a Streetpass function that lets you challenge the Mii of any player you come into contact with, but the tennis mechanics are the same as elsewhere, and with the AI taking control of your opponent's Mii, it offers little more than the same thing as elsewhere under a slightly different menu option.
Four minigames are present to provide a brief distraction. These all involve hitting balls in certain directions, either to pass through rings, collect star pieces, or avoid an opponent. The best minigame features levels from Super Mario Bros. on a video screen, with the tennis ball acting as Mario. You hit the ball at various parts of the level to scroll it forward, collect coins, and defeat enemies. It's fun for a little while, but even this minigame quickly gets old. Minigames reward you with coins, which can be used to purchase outfits for your playable Mii character. Outfits are unlocked for purchase by playing tournaments and matches, so if you're looking to own everything, you're in for a huge amount of grinding and repetition.
Even then, there's very little to keep you coming back for long--the tennis just isn't exciting enough. It lacks the subtleties of more realistic tennis games, but is also missing the grandiose moveset of other Mario Sports titles. The changes brought on by the different control methods convolute an otherwise basic game, and there's not enough substance--or enough skill required--for Mario Tennis Open to be treated as a serious tennis game. Playing against friends can be fun, but this is otherwise a rather uneventful, forgettable instalment.