Whether you are a fan of Tetris Attack or just puzzle games in general, you need to play this game.
The single player half of the game features 6 different types of game modes: Time Attack (try to get the highest score in 2 minutes), Puzzle (features different scenarios ranging from easy to very hard), Endless (keep playing until you get a game over), Clear (clear all blocks above an indicated line), Garbage Attack (similar to Endless Mode, only this time garbage will keep falling on you), and Vs. Computer (self-explanatory). This game also features a "Daily Play" mode, which gives you 3 different game modes (Lift, Garbage, and Score Attack) to play for 2 minutes, then records your scores on a chart and compares it to earlier scores. There is also an option to add items into the mix, but I would leave this feature turned off as it makes the game easier or harder depending on what you get. The effect of some of these items include: transferring all the garbage on your screen to your opponents screen, shuffling your opponents panels, making all of your cleared blocks count as a combo for a short time, and more. It sounds like an interesting addition to the gameplay, but it could've used a little more customization (ie choosing which items you want to use in game).
Also included for the first time in the series is online multiplayer, letting you play against one of your friends using friend codes, or free play mode, which lets you play a random person from around the world. If you are a newcomer to the series, I would just stay away from multiplayer until you get some skill at the game, because 90% of the time you will be playing against people who could probably beat you in under 30 seconds. It also features a Birthday Battle mode, which (just like the items addition) could've been tweaked more. All it basically is is a ranking system, but in order to play in this mode, you have to find someone with the same birthday as you. Of course you can make this less of a hassle by going on a forum and telling people to set their birthday to a specific date and battle that way.
Graphics: Graphics are more or less the same as they were in Tetris Attack and Pokemon Puzzle League. Theres 7 different types of panels, including the classic panels from Tetris Attack. Theres also 10 different stages each with their own unique theme and music. No, this game does'nt have a Mario or Pokemon theme, but instead has it's own techno-esque theme to it.
Sound: The sound in this game has sort of a techno / rave theme to it. Its probably not the best music in the world, but some stages have some catchy tunes to them.
Value: While single player can be fun, multiplayer is where its at. Once you master single player you will probably be playing multiplayer all the time.
Overall: Planet Puzzle League is a game that should not be missed by anyone who owns a DS.