Sonic Rush is an amazing burst of speed from start to the end.
The special stages, where you have to get the emeralds, are a lot of fun. Similar to the Sonic The Hedgehog 2's special stage game on the Mega Drive / Genesis released in 1992, you race down a half-pipe collecting rings, avoiding bombs and jumping at robots. You use the stylus to control Sonic instead to the d-pad.
The music fits the fast pace of the game and the sound effects are great too. Many of the gameplay elements are similar to the old school Sonic games. I'd have liked to have seen some more classic features in the game, such as an selection of badniks from previous games.
It's hard to fault Sonic Rush. It's challenging, always fun, fast and funky :)