If I'm going to be 100% honest, Sonic 1 is an okay movie. I know everyone compares it to Hop and all, but be real; Is anyone THAT harsh about Hop? It's an inoffensive kid's film, and Sonic 1 is an inoffensive kid's film. It's not exactly peak cinema, but there's nothing terrible about it. It's a perfectly servicable movie.
That said, it's not a good Sonic movie. I know I just said it's an okay movie, but that was just based on the actual structure of the film itself. The main problem with the Sonic movie is that it's about Sonic.
Sonic is a character people have passion for. Sonic is a character people were excited to see come to the big screen. So even though I think Sonic 1 is a fine movie, I can't exactly blame diehard Sonic fans for having problems with the movie we got. Sonic shouldn't have gotten a generic buddy cop movie, even if said buddy cop movie isn't terrible.
It's a situation very similar to Banjo-Kazooie: Nuts & Bolts. Technically speaking, the game is solid and can actually be pretty fun (although it does have its issues). The problem stems from the fact that the Banjo-Kazooie IP was attached; It had been years since Banjo-Tooie, so people were naturally upset that N&B wasn't entirely in line with the original duology of games.
(This isn't to say that critique towards N&B or the Sonic movies based on the source material isn't valid; Both products could have done more to be more faithful to their original source material without entirely losing their vision and still being fine, and the former could have been more upfront with its goals during promotion. I'm just saying that I consider the backlash towards the two products comes from a very similar place.)
To try and wrap things up, I will restate that the first Sonic movie, while not a bad film in principle, strayed too far away from the source material without doing enough to justify its deviations from the Sonic games, and it's completely understandable why many Sonic fans are turned off by it. It's a fine movie, but it's not a Sonic movie.
In any case, though, Sonic 2 seems to be striving to remedy this problem at least partially, and I am confident in saying that it'll be better than the first movie.
tl;dr: y'all owe the angry birds movie an apology