A master of disappointment.
The major feature of Wario: Master of Disguise is... well, the disguises. Over the course of the game, you unlock new disguises, each granting new powers. The space suit gives you a laser, the dragon costume lets you breathe fire, the genius costume lets you see invisible doors and platforms, and so on. You keep unlocking these well into the game, as well as new powers for each of them, and you can go back to previous levels to reach previously inaccessible areas, adding a bit of replay value.
Changing costumes is done by drawing a symbol on Wario with the stylus. The thing is, though, the game doesn't always do a good job of recognizing what you're trying to draw. It's simple early on when you don't have that many costumes, but as you keep unlocking them, it becomes that much easier for the game to get confused. While it's not too big a deal while exploring the levels, where you can take your time, you don't have time during most boss battles to bungle around with the disguises until the game gives you what you want. Mega Man's been changing forms more easily for years with a pause menu or the shoulder buttons, and it could've been done here as well. It's not so hard to deal with that it makes the game unbeatable, though, but it's still frustrating as it is.
In addition, the artist costume's abilities revolve entirely around drawing on the Touch Screen. You can create blocks, which is done by drawing a square, and health-restoring hearts by drawing... well, a heart. If the game doesn't think your drawing is square-ish or heart-ish enough, it becomes a walking poo (no, seriously) and you just wasted a few seconds. Once again, that's something you don't want to happen during a boss battle.
Since the action requires you to keep the stylus in one hand for all the Touch Screen usage, the movement controls have been mapped to the D-Pad and the letter buttons. That is to say, they both have the same functions, for lefties or righties. This includes jumping, set to Up or X. It feels a little weird using the same hand to move and jump, but it's actually easy to get used to. It makes it easier to grab ladders in mid-jump, that's for sure.
As with Wario's past adventures, there's treasure to be found. Scattered though levels are treasure chests containing not only treasures, but new disguises, health upgrades, and key items for the level you're in. Standing between you and every one of these items, though, is a Touch Screen-based mini-game. These include connecting dots, coloring pictures, and (ugh) sliding tile puzzles. There's only eight different kinds of mini-games, and they're not that challenging, either, even as they increase in difficulty. You eventually get sick of seeing the same eight games over and over again.
To call Wario: Master of Disguise just a platformer wouldn't be totally accurate. There's a good deal of puzzle solving to do to get around each level, which requires the abilities of the disguises. However, there's not much variety. Much of it is just switch-shooting with the space suit, or using the artist's blocks to reach elevated crawl spaces and weigh down buttons.
The levels are huge and elaborate, and it's not often clear where you're supposed to go next. Due to the maze-like layout of the levels, it's easy to get lost and end up backtracking over the same rooms over and over, even when you have the level map. It doesn't help that certain obstacles and puzzles reset when you leave the room, and must be dealt with every time you enter. It's not unusual to take over half an hour (maybe even a whole hour) to beat a level with all of this in your way. At least it gives the game length, even if it's in an annoying way – There's only 10 levels, but it'll certainly take a long time to finish.
The sound is okay, but nothing special – Besides Wario's mad laughter, there's nothing noteworthy about the sound effects. The music isn't catchy, but at least it's well-suited for the environments. As for the graphics, most of the levels and enemies look so generic and dull for a game starring someone who hangs out with Mario. They're like what you'd find in one of those SNES games that's supposed to be based on a kid's movie, but it barely follows the movie and throws in a bunch of environments and enemies that weren't in the movie because it didn't have enough stuff trying to kill the hero. They just doesn't have that Wario feel.
Wario: Master of Disguise is certainly not up to the level of quality that's worthy of Wario. While Wario games often try to be different from other games, this one tries to make more use of the Touch Screen than it really needs. The confusing level design, average graphics and sound, and annoying mini-games drag it down as well. You could do worse if you're looking for a platformer on the DS, but more importantly, you could do better.