Has some interesting ideas and isn't wholly bad, but parts of it are almost unbearable to play.

The base gameplay is actually pretty fun, but where the game suffers is through its mission structure, where if you want to unlock certain levels you have to defeat every single enemy of a certain type in the level. Missed one of them? Guess what, you have to replay the entire level again except it's totally empty and boring now until you find the single enemy you didn't kill. The level design is also pretty poor, with Mad Matrix and The Doom standing out as two of the most frustrating stages to play through, the latter taking me almost two hours to complete due how badly laid-out the level is combined with the fact that the game forces you to search every last corner of the map without giving you any indication of where you've been or where you need to go.

There's a lot of Sonic Team charm to it even amongst the gritty attempt at making a mature Sonic game, and there are certainly things I like about it (the soundtrack is arguably one of the best in the series), but overall, it's not very good.