Sonic's DS debut ends up being a surprisingly good time, blending the old with the new and making it work.
Graphics:9
For a DS game, this is very good-looking. Environments look great, and they mix 2D sprites with 3D models rather well. Some of the effects could have looked better, but that is only a minor annoyance.
Sound:9
Voice acting is in. That's the bad news. The good news is that there isn't really that much compared to other Sonic games - conversations usually blend minimal amounts of voice acting with text, so just be prepared to read. Music in the game is mostly techno, and hardly any of it will get on your nerves. Sound effects are what you expect from the series, along with some new ones thrown in.
Gameplay:8
The story blends with the gameplay almost seamlessly. You never really spend much time on the world map, and the stages are designed mostly for speed. Blaze plays a little differently than Sonic, and is the easier story of the two. You get a navigator to help pan out the course for you - Sonic gets Tails, and Blaze gets Cream the Rabbit, who immediately becomes friends with Blaze, much to the cat's chagrin. Although everyone around Blaze is friendly, you can tell Blaze herself just wants to blatantly scream, "I WALK ALONE!!!" and get the hell out of sight. You get back the Sol Emeralds just by going through Blaze's story, but you have to play the Special Stages as Sonic to get the Chaos Emeralds. It can get a little frustrating at times, especially some bosses and Special Stages, but the gameplay itself is good.
Multiplayer is in, but only Battle Mode, where you get to see who can get through a stage faster - you or the opponent. One of you is Sonic, the other Blaze. Pick a stage and have a blast.
Replay Value:7
There's just something about the storyline that'll make you want to continue to come back for more. 2 different difficulty levels give you the option to challenge yourself, you can unlock Time Attack so you can try your hardest to speed-run a stage, and you can also see how much time it takes for you to beat a boss. But it gets boring after a while.
Overall, Sonic Rush is a good way for Sonic to debut on the DS. Sonic fans old and new will find something to love about Sonic Rush, and if you haven't played any Sonic game at all(and why haven't you?), this is probably the best way to introduce yourself to the series.