Asymmetrical gameplay is nothing new to Nintendo. Pac-Man Vs. allowed players to experience the series as the bad guy for the first time, while Super Mario Galaxy 1 and 2 gave the second player to assist the "main" player from a distance as an off-screen, intangible, sparkle-shooting deity. Rayman Legends allows for a little bit of both of those concepts. Players utilizing the Wii U GamePad can both assist the main player, or screw with him/her if they're feeling mischievous.
It's a lot like Boost mode in the upcoming New Super Mario Bros. U, but with more level-specific applications. Where Boost mode allows you to create blocks under-foot or stun enemies for a second, Rayman Legends' asymmetrical gamplay has the "main" player and the assistant working through puzzles and environmental hazards that would be impossible for a single player to tackle alone. That makes for a situation where the player with the Wii U GamePad feels more important than they might in New Super Mario Bros. U, while the "main" player is left feeling slightly more dependent on their off-screen companion.
Regardless of which does asymmetrical gameplay better, I'm just excited that they both of these games exists. Seeing not one but two traditional, 2D platformers making their debut as flagship exclusives for the Wii U is almost spit-take worthy. There was a time when the genre was all but dead. Having it back in the spotlight is a wonderful thing.