Sonic and the Secret Rings. Not necessarily worse than Sonic 06, since I've never played that myself, but from what I remember, SatSR was a god-awful, confusing mess that repeatedly gave me unclear objectives with restrictive time limits, and terrible "cinematic" cameras - yeah, sure, it looks real cool to be running away from that hoard of dinosaurs, but that doesn't help when I get hit by, or DIE FROM, a hazard that I had no way to avoid! I would rather have been running from an unknown pursuer, and been able to SEE WHAT WAS IN FRONT OF SONIC.