Sonic the Hedgehog: The Movie is a Japanese cartoon based off the Sonic series. This is unusual since most of the Sonic cartoons and comics were made by American studios. I'm reviewing the English dub by the way. So, that's why I am not crediting the Japanese actors and referring to Doctor Eggman as "Doctor Robotnik".
The plot is that the super-fast, blue hedgehog Sonic (Martin Burke) and the flying, two-tailed fox Tails (Lainie Fraiser) are assigned by the President (Edwin Neal) of the Land of the Sky to go into the Robotropolis, the capital of the Land of Darkness. Metal Robotnik (Edwin Neal) has kicked out Doctor Robotnik (Edwin Neal), the tyrannic ruler of the Land of Darkness, and is going to unintentionally cause the Robot Generator (a machine Doctor Robotnik uses to build robots and power his city) to explode. On the way, Knuckles (Bill Wise), a flying echidna (I know he glides in the games, but he clearly flies in this), joins them on their quest.
Let's look at the good aspects. They do a fair job with explaining the new elements they introduced. From what little know about the game, the movie is very accurate to the games. While the art isn't good, it isn't that bad. The actions scenes are good save for the last act.
Now, let's look at the bad aspects. Newcomers will be confused because the elements lifted from the games' story lines aren't explained very well (if at all). The last act of the film basically devolve into one overlong and boring fight scene. The president and his daughter, Sara (Sascha Biesi), are completely pointless. Sara comes off as really annoying. The movie tries to add comedic scenes, but fail at making you laugh. Dr. Robotnik, despite arguably being the main villain, doesn't come off as a real threat and a villain (Gary Dehan), introduced the last act, takes the spotlight away from him. While they do explain a lot of the new elements, there are somethings that aren't. For example, why does Robotnik remain in the Land of the Darkness when he can seemly easily just kill the president and take over the Land of the Sky? There are no background extras to the point that it seems like the Land of the Sky has only four or five people living there. The voice acts is terrible (although you get use to it).
I'm going to give two scores for this movie. For a fan, they will probably like this. As such, for a fan, it would get a 3 out of 5. However for a non-fan or newcomers, this movie gets a 2 out of 5.