Sonic Rush is everything that made the Genesis classics great and more. You've got your sense of speed, great boss fights, and you don't have any superfluous characters being shoved down your throat.
The game looks and sounds great. This is Sonic in a 2.5D adventure; a first for the series. The character models are in 3D, and the levels and backgrounds are all in brilliantly colored 2D. You couldn't ask anything more from a DS title. The music is catchy and always seems to suit the situation. As the gameplay speeds up, the music does too. If your time limit is running down, the music gets a panicky feel to it, and it really gets your heart going.
The gameplay is a fresh take on a classic formula. You've got your standard "press right to win" going on, but things are complicated (in a good way) by the two screens of the DS. You'll be running and end up going from one screen straight over to the other depending on your direction and momentum. You've also got a speed burst, activated by pressing a button. Your speed burst is good for two things: killing enemies and making quick escapes. You build up your burst meter by doing tricks in the air, which amounts to nothing more than pressing a few buttons as you fall. If you happen to fill your meter completely before using your speed burst, you gain invincibility for a short time. What this game does really well, as the name would imply, is maintain its sense of speed. Sonic is about going fast, and you'll do just that in this title.
The boss fights are very well-done. You all know the drill: Robotnik jumps into a giant robot and tries to squash you. You'll be chasing sea dragons, jumping over steam-rollers, jumping on heads, and spin dashing all over the place. Hard to find any issues there.
We also get to meet Blaze the Cat in this game. The story of this title revolves around her. The story is incredibly simple, but I think that's what a Sonic fan wants. You aren't going to find yourself skipping through endless menus trying to get to the action. Here's the gist of it: There are two dimensions. Sonic is from one, Blaze is from the other. Each has its own version of Robotnik, and they've met up because the universes somehow came together. Playing as either Sonic or Blaze, you progress through the levels in an effort to stop them. Everything controls as it should, and you don't suffer from "cheap deaths" like you might in some other Sonic games from running too fast and finding an unexpected cliff.
The multiplayer is what you might expect: you race your friend to the end of the level. You only need one cart to play with a friend, and you can also send a demo of the game to them. It's a fun distraction, but ultimately not the focus of the game.
There are a few faults with the game, but nothing major. Sonic veterans may find it a little easy at first, but some of the later zones and boss fights can be quite the challenge. The story is cheesy and shallow, but that could be a good or bad thing for a Sonic fan, depending on who you ask. Without a doubt, the largest issue with this game is the length. It is in-arguably too short, but the replay value is high with fun multiplayer, two difficulty levels, and two characters.
Overall, this is one of the better handheld Sonic packages out there. It is essentially an extension of the excellent Sonic Advance series, and it manages to improve upon the previous games in every way. It's an incredible deal for the price, and you owe it to yourself if you like Sonic or 2D platforming games in general.