A very solid entry in the franchise, while not completely perfect, it has a lot of great things about it and it's one of the Sonic games that a majority of people will say is good. It's a pretty short game, completing it at 4 hours, but replaying it after clearing every other mainline Sonic game before feels pretty rewarding. The Classic stages can be a little meh sometimes, but they're still pretty easy to breeze through and the Modern stages make up for it for feeling a lot smoother and faster, though they have quite a bit of 2D elements despite the Classic and Modern differences being 2D and 3D. The game is also really easy, which is fine, but makes me less likely to replay it compared to something like Unleashed or Adventure 2 which can be challenging at times due to it's gimmicks or level design. This can be excused because this game should be easy, it's a celebration of the 20th anniversary of Sonic and all of the games that came before. The soundtrack has pretty decent remixes, though I prefer a lot of the original songs a lot more. The Classic remixes are alright at best and not really for me, though the Modern remixes are a lot more of my style even if they aren't better than the original. Overall, I'd say this game is pretty solid and does what it needs to best for a great celebration of Sonic's 20th year.