Its still decent but it feels primative.
Now the gameplay is the old dreamcast one. Mske it to the end of the levels, collect the 3 emeralds, beat sonic, escape from zero, etc. THe boss fights are decent but seem to easy at times especially for older players. The extra missions are fun but some are frustrating. (ex. "find the damn 3 pieces of the master emerald in less than 1 min. in the hardest place". WTF?) The chao is fun but it isnt as good as the sonic 2 one. The new additions, mission mode and and old sonic" are fun for a while but they dont really add much.
Overall it is a great game for fans or people who didnt play the original or you just a good time with something from the past. Other than that approach this game with caution since you can have better. Compliments of age. But you can really go wrong with the double pack version of this game and sonic 2 battle, as yours for a low 30$.