Mario loses a dimension but gains the ability to turn himself into a paper plane. Sounds like a fair swap to us.
Nintendo have just launched a Japanese website for Paper Mario 2 - and it includes a brand new movie that features over two minutes of footage of the game in action. As evidenced by the new trailer, this sequel to the Nintendo 64 RPG features 2D style graphics in a 3D world, and gives Mario the ability to turn himself into a variety of objects (paper plane, tube) to help him traverse the game"s worlds.