Formulaic, a little bit silly and too violent for small children. The ending was obvious about an hour off from the film's end.
Also the lead villain (Jim Carey) is nothing like the fat sprite in the video game. Sonic has also developed warp speed and super powers which he doesn't have in the game. His relative lack of power in the vids is what made him a charming character. Now he is like a marvel super hero.
It's a duff film. I guess most of the people giving 5 stars must have been paid to do so.