There's your problem, Chibo. You're playing the Wii version. ROFLOL
You miss out on what makes a Sonic adventure (no pun intended) feel complete in the new age of gaming. I find the Werehog levels are frustrating on the 360 version (they work, control wise they work just fine, but it's the dying and losing your points factor that annoys me), but the daylight levels are extremely fun. Trust me, you'll get a real kick out of them. And on rails? I know you mean it FEELS like it when it's not, but wasn't it the same way with the original Sonic games? The entire objective is to move forward constantly as fast as you can. Heck, even the daylight levels have SOME platforming involved where you may need to slow down. Maybe it's not as apparent in the Wii and PS2 version...but they exist.
Stopping cold in mid-air, to SEGA, as time slows for you, makes it feel urgent. Like, "Oh man... If I press these buttons right, something awesome's going to happen." And so you do it right, and you go on a different trail where most of the time, you're in for a wild burst of speed. It adds variety, maybe not a lot, but it's a tiny bit of something in what would otherwise be the constantly running blue hedgehog we've come to know over the years.
You're missing out. The Wii version feels like an incomplete version of a better Sonic game on the next generations of 360 and PS3. That's me, anyway, and probably many others.
Give it a spin!