Great game
The story:(Spoilers) It all takes place after sonic 2 and you and tails have just defected robotniks death egg and are traveling to angel island were you run into knukles who has been tricked by eggman to think that you are here to steal the master emerald. Ohh but dont think thats the whole story since the rest takes place in sonic and knuckles.
The gameplay: This hasnt changed much at all since the sonic 2 and there isnt much to say about it other than its still really a fun and fast game to play.
The music: Its just as good as sonic 2 but sounds alot differant and has some songs that can get boring after a while and others that are just masterpieces like ice cap.
The graphics: Everything about this game is unique and colorful the backgrounds in the stages are more complex and colorful and sonic has a new but good look to him that still to this day looks really really good and not dated at all
Overall : sonic 3 is just as good as a game as sonic 1 and 2 and must be played by fans of the series.