Neat for an April Fool's joke, I guess. The art is cool, but the story/mystery itself is pretty bad (despite only being two hours in length). Additionally, the lack of a text log is surprising given it's a VN format. It certainly has its charm, though.

Edit: I'm not a Sonic fan, so reading other reviews that WERE written by Sonic fans saying that this is one of the greatest Sonic games they've released in recent years... man. Now I really feel sorry for you guys. Not in a condescending way, though, I just hope things get better.