Never personally played it, but from a viewer perspective it's looks pretty bad. Sure, the graphics are good for 2011, the level design looks good, the minigames can be fun and the overall idea of a "museum" game is pretty cool.
Unfortunately, the positive aspects end there. No offense against Pont and Graff, but this is quite possibly the worst story written in all of fiction! I understand Sonic is targeted towards kids and I don't expect a beautiful novel as a story for a kids game, but there needs to be a good story in order for your game to be playable. Doesn't help how Sonic Adventure 2 and Sonic 06, two of the earlier anniversary games, had WAY better stories and writing, so there's no excuse to this kind of writing.
Other problems include how short the game is and how Sonic's friends do nothing but say a few lines and do something in minigames (besides Tails, Shadow and Silver; 2 of which are bosses). I wish they just made more characters playable in modern Sonic.
In conclusion: 1998-2009 were the best times for Sonic and Co. As characters and for their stories.
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