Simply put, Rayman DS is a prime example of how not to do a port.
Essentially last-generation's classic Rayman 2 title shrunk down to a bite-size cart, almost everything that made the game enjoyable was lost in translation: The whimsical colors of Rayman's world are now washed out and dull, controlling Rayman accurately is way too difficult with either D-pad or (especially) the stylus.
This game's aesthetics and mechanics have both been butchered in their transition to the DS, and as such, should be avoided at all costs. Hungry DS owners are probably tired of hearing this, but please: do yourself a favor and run through Mario 64 again.