Jam Sessions DS review at PALGN.

"When is a game not a game? When it's art, apparently. Games like Electroplankton and Line Rider have pushed the boundaries of what we understand as a 'game' by removing the ability to 'win' - instead, as with any real sandbox, creativity's the order of the day. Sounds good, right? Unlimited freedom, unrestrained creativity, and play free of boundaries? Unfortunately, the most common side effect of such unfettered freedom is ironically one of boredom - while one's free to do whatever they want, the game still operates within a (normally) highly limited set of hard and fast rules. For the vast majority of people, once the player exhausts exploring the dynamics of these rules, the game is effectively 'over' - enjoyment comes from discovery, not creation. And, in a nutshell, that's the dilemma that faces Jam Sessions."

Full Source: PALGN