Tetris is a solid addition to any puzzle fans DS library.
Gameplay: A ton (8) of gameplay modes including multiplayer and wi-fi internet play make this game worth every penny. The whole presentation is done well. The touch features of the DS are incorporated enough to make it a point to mention, but it's also not to much of a gimmick.
Sound: The music consists of remixed classic Nintendo themes. All are sound great. The sound effects are also nice and again Nintendo themed.
Extras/Unlockables: The only real goodies to unlock or complete are the puzzles in the similarly named mode. Also you get something for clearing 200 lines in marathon mode. I would have liked a more rewarding style of game, but really I can't complain too much.
To sum things up, this is a great Tetris game. Since I first got my DS I've been waiting to play Tetris, and with the inclusion of online wi-fi play; this game is everything I could have hoped for.