A lot of people are unhappy with the software available for the DS but this is the best yet if you can give it a chance.
User Rating: 9.1 | Yoshi Touch & Go DS
There's a lot of bellyaching about how this isn't a platformer or how this isn't an adventure game. There's also a lot of complaining about how there are only "two levels" in the game, and how Nintendo merely packaged the tech demo to make a quick buck. As for the first complaint: get over it. This isn't an adventure game and it never claimed to be. As for the second: this is mostly untrue. There are, in fact, two different games - the vertical falling mario and the horizontal yoshi - but there are a number of different levels for each. How many points you score in the mario stage determines what type of yoshi you get (which affects how fast you travel and how many eggs you can carry) and how difficult the yoshi stage will be (how many enemies there are and how rare the egg-replenishing fruit is). Once you learn how to steer baby mario, you will see the difficulty increase in the yoshi stage at the same pace. There are randomly generated levels in some of the modes, so that the only thing you've seen before is the background. The bottom line is that this game plays very well. It is more of a puzzle game, in that there is no end and you can always do better. Once you learn how to steer mario and yoshi using the clouds, you'll start trying to round up the other coins and enemies on the bottom screen by drawing bubbles. If you can learn to manage the entire bottom screen, than you can start trying to catch all the stuff passing you on the top screen. All the while, the game throws more things at you as your skills develop. The gameplay is great. The touch screen allows for a very quick and hectic gaming experience. You are surrounded by potential actions that are merely a twitch of your hand away. The graphics are alright (I would have preferred to have seen them a little more stylized like Yoshi's Island, but it is crisp and colorful), there isn't anything wrong wth the sound, and the game is a damn good value for $30. This is the best original game out there for the DS. So, while we're all waiting for online Advance Wars, Animal Crossing, and Metroid, lets just try and appreciate how this is the only game beside Mario 64 to make a DS worth having in the mean time. 
