Sonic CD was one of the best Sonic titles to grace humanity.
With the introduction of Metal Sonic and the first time cinematic intro/outro, I knew this game was something special.
The maps have a very good flow to them, and the past/future redesigns add that something special to really bring this game together.
The bosses, albeit weak in some situations (First boss is a total pushover) are very unique and forces the player to think ouside of the box in order to defeat them.
The boss designs are also very unique and cater to the level designs to form a very fun experience; For example, the Pinball boss in Collision Chaos, or the Treadmill boss in Quartz Quadrant.
The only downside to this remarkable game is the special stages, where though the gameplay takes a drastic change into a 3'rd person perspective and again, forces the player to strategize, the difficulty unfairly ramps up after the fifth special stage to unplayable proportions.
Overall, a very fun game with lots of replay value.
Definately a must have for any respectable gamer.