Sonic the Hedgehog 3

The Good
On its own, it's a good game, but when locked on with Sonic & Knuckles it becomes 100 times better. By locking on to Sonic & Knuckles you get to play the full version of Sonic 3, the way it was meant to be. You get more levels, mini games, the ability for all characters to turn super or hyper, the ability to play as Knuckles, and several other cool features. Sonic 3 is only the first half of the game; Sonic & Knuckles is the other half. Lock them both together and you get the complete version of Sonic 3.

The Bad
Sonic 3 by itself has some bugs, but locking it on to Sonic & Knuckles fixes them. So, there really isn't anything bad about the game. Just play both games together and all the bugs are gone.

The Bottom Line
If you liked Sonic & Knuckles, you should definitely get this game. It's the other half of the game. Remember, you haven't really completed a game yet if you've only played half of it.