Yeah, I really liked it too (albeit I never owned it).
It wasn't as high paced as most of the other Sonics, and I liked that. You had a bit more control.
Also, chao garden is awesome beyond words :D (it's a bit ironic that I wrote that...)
I hated being Rogue/Knuckles though... Luckily, my friend (who owned it) liked them the most.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS