Sorry KK, but I have to disagree with you here.
I think it's comparing two different things when you're talking about making concessions between a book and a movie, and comparing how a video game character looks in a movie. Yes, there are concessions to be made in book-to-screen adaptations, but with books, there's very rarely a visual element. Everything is created in the reader's imagination, and not all events from a book can be included in a movie, purely because it would cost too much and the movie would be too long.
When it comes to something as fundamental as to how a character looks in a video-game-to-movie adaptation, concessions can't really be made. The character has to look as iconic as it does in the game. Yes, of course, it's an adaptation so you can't just plonk a CGI character in a live-action world, but the recreation has to be very, very similar to the original. It's only natural that there are going to be complaints if it's too different.
I don't think we can even use the excuse of saying it's what Sonic would look like were he in our world, purely because in real life, there's no such thing as alien, sneaker-wearing blue hedgehogs that run at the speed of sound. Nobody is going to think 'Oh, this is what alien, super-fast, sneaker-wearing blue hedgehogs that run at the speed of sound look like in reality' because there's no such thing. Therefore, you have to go with the visual that people have already because that's all they know. That's all they can relate it to. That's what their nostalgia and love of the character are based upon. If you're making a movie, you can't just take the most basic elements of Sonic (i.e. that he's blue and wears sneakers) and morph it into something else entirely.
I think the design of Sonic was awful. For some reason, they really elongated his body, but reduced the big facial features of Sonic's that we know and love. He just looks very weird, and as
@Turo602 said above, there are fan creations that are way more true to Sonic but also don't look out of place. I mean, I'm not gonna watch the movie anyway because I think it looks terrible (Jim Carrey is just so cringey as Eggman), and I don't like the whole 'let's make this movie about the human world and make a story about Sonic bend to it' approach. But when it comes to a fundamental thing like how Sonic looks, it has to be done right.