Eh.
I never actually remembered waiting 4 years, sure, I watched a trailer, but never seemed to actually care. However, animation, body form, and just plain quality just seemed to be better in the trailer and in some other works as well.
No voices? Not even subtitles? That was an issue. It was hard to understand anything at all. Not to mention the story seemed weak, and the only hint at story was the brief synopsis that works only when there's speaking or at least read roles within the animation. Have you seen Super Mario Bros. Z? There are actual voice clips taken from the games, short words, grunts, that are played along with the animation. I did also notice a lack of sound effects. Sound effects, and sound as a whole that is separated from the shredding guitar in the background adds completeness and wholeness to the animation.
Where animation is concerned, Knuckles was the worst drawn and animated in this film, and that's horrible since he's my favorite character. It looked like it was pulled out of Sonic: Uncut, a joke series that isn't so beautifully animated nor tries to be. I see you did work hard on things like the Egg-o-matic, which was done beautifully, but certain things like the lines on Eggman's coat had depth issues that confused your eyes.
I don't really understand what all this hype is about, but I do understand the amount of mixed reviews you'd probably get. This thing confuses me, it doesn't actually work out in my opinion. Maybe if you revisited it, or you redid it, some light would appear at the end of the tunnel, but for now, there's a giant boulder blocking the way.