One word: why?
So what's wrong with this game exactly? A better question would be what's right with it! For starters, why a Sonic title that removes the speed? I'm beginning to think that this wasn't even a Sonic game to begin with. They just threw him in there at the last second and said, "hey, we've got another Sonic game under our belt. Job well done, gentlemen!".
Job well done indeed. But you forgot one tiny important aspect that's vital for any game, and that's the fun.
You spend your time looking for keys to move onto the next poorly designed level and eventually a tough-as-nails boss. Now if this was all handled smoothly than things would be just peachy! But that's not the case here. Sonic controls like a tank and can't even match the speed of one. Now throw in some annoying enemies and an unforgiving timer on top of it all and you got yourself Sonic Labyrinth! Is there some reward for having to suffer through this afterthought of a game? No. Your only reward is getting to shut the system down and letting the game rot in a thick layer of dust!
If you're a die-hard Sonic fan, you'll regret purchasing this one. If you hate the blue blur for all he's worth, then this will only increase that hate beyond any convincing! But if you desperately want to try this one out despite what others say, than may the heaven's have mercy on your soul!