If you're going into this movie expecting it to be perfectly 1:1 to Sonic Adventure 2... don't. It's not trying to be. That's not what it is, not what it's supposed to be, and you're a fool if that's what you expect despite the fact that trailer itself shows Gerald alive when he was dead in Sonic Adventure 2. This is one of the movies, whicj means it's part of the movie timeline and not the games, which has already been shown to be different from the game timeline over the course of 2 films, which means you have had 2 whole movies already to get it through your thick skulls that these arent trying to be just the games all over again. They pull elements from the games of course, but they're largely meant to be their own thing.
TLDR: The movie is its own good thing, and the people giving it one star for not just being a 1:1 clone of Sonic Adventure 2 missed the point entirely