I don't know what kinda coke Rotten Tomatoes, IMDb, Indie Wire, and the rest of the 1 and 2 star shart reviews are snorting but they are CLEARLY on some kinda funky junk to rate the movie that low.
The movie was amazing, from the choice in new and re-occuring V.A.'s and Actors/ Actresses, to the 3D animation, right down to the story. An absolute smash hit. You can really tell that the 3D animators got a bigger budget w/ how the models look compared to the first movie.
There was also the slow evolution of Sonic's relationship w/ Tom and Maddie that was a fantastic added touch.
The attention to detail in regards to the various characters traits were on par w/ the franchise in a whole, especially Tails and his gadgets.
---NOTE: this does NOT retell the story of Sonic 2. If your watching this after watching the first film and thinking it's going to follow the same story as the games, you got some screws loose, especially considering the movie features Knuckles who WAS NOT featured in Sonic 2(the genesis game) or it's story.---