Needs tons of work
This was good, but not great. There were many overall problems. These include movement, such as running with the screen scrolling, and the falling very far down very slow, or jumping very high. It was slow even on high detail. It needs to be faster and smoother. Next, Shadow's arm movement was totally incorrect when running, there is now way it would look so gay. Also his hand clenching thing was terrible when he stood still. Some animations were overused. (I voted 5 for the effort, prepare for a rant!)
Now for the main movie. The a story line is not established at all. The music was overused and annoying after awhile. Sonic would not sneak attack like he did when Shadow kills the mechas. Knuckles would not hit the master emerald at someone. Tails disappears later to be caught by Robotnik with no reason why or how. Many fighting animations overused. The movement problem mentioned above made me bored and the line effect when they were falling was like an old tv set.
The best alt ending was the big clash. The rpg game was good, but could use a char. choice. The hill zone was terrible. The other alt. endings, especially mechas win were bad. The outtakes were good.