The problem with 3d sonic is quite a few things.
Game Mechanics...sonic games need to be fast...at the same time you need to control your character. It seems the new trend with 3d sonic is they like to have this mix of slow combat and on rails combat/running. The homing spin is probably the worst thing ever done to sonic. Yes it allows us to attack while speeding along...but does it take any skill? Do you feel like you accomplished anything cool and stylish? NO and NO. Old sonic games had lots of different ways to traverse the terrain and a mistake while maneuvering and fighting at break neck speeds simply had you falling to the next. Sonic is stylish when errors can still flow. Grinding a stupid rail and missing a jump and restarting without any freedom sucks balls. Why not make a TON of valid rails and have enemies that can be attack along the way that could give access to better paths if attacked properly. You need that feeling of reward when you do something fast and intricate on the spot. Having to die and restart on some boring on rails routine is tiring and lame.
I say add an area of effect attack while airborne that can home on to an opponent for a cool bounce...if your close though. This float in air slowly then pop the enemy guaranteed attack sucks and has no flare to it.
The characters and story. They need to stop fuckin things up here! Ok we got tails...cool, we got knuckles...really cool...then we got like 45 other fuckers and hedgehogs...THAT CAN ALL RUN ASS FAST AS SONIC AND DO MORE!!! What the fuck is so special about sonic anymore?!? Also Eggman...what the fucking fuck Batman? It's Robotnik...and yes I have smacked a small child for trying to tell me it's Eggman and not Dr Robotnik. Stop with the name changes, stop making sonic obsolete, and create some characters that are interesting rather than buff the online sex life of the yiffing furry elites.
Also stop giving sonic stupid gimicks...Werehog: bad idea, Sword: really bad idea, Shadow gets a gun: Ok...who's giving reach arounds at this office to get this shit passed (I want their number with that kind of "skill").
The worst part about Sonic Team? They repeatedly get horrible reviews and have people point out EXACTLY whats wrong with the game and they still keep fucking up. It's like changing a diaper on a soiled infant only to have it shit on you while trying to fetch it a new one.
Damnit! where's Yahtzee?!? [/rant]
P.S. Sonic 3+Knuckles was godlike!