Summary: I am a huge fan of the Sonic games in general, but this game was way to frenetic for me. The fact that the game goes between the two screens on the DS as you're moving through the levels makes it very difficult to figure out where you are at any given time. Since time is a factor in your score, trying to get through a level quickly is nearly impossible to make sure you're hitting the bonuses.
Conclusion: When I first got this game, I thought, "Oh, great! its got good ratings and good reviews. Quite cheap as well. This has got to be good!" How wrong I was. There are hardly any levels at all, and it is all over and done with in a matter of days. I myself, am 11 (my mums account obviously), and I completely finished this game in about 2 days. I literally asked myself, "What, has it finished?" and it was quite a lame ending.