Sonic Generations could've been so much more but severe lack of content, strange mechanics and difficulty hold it back.
First off, I will say that in the visuals and music, Sega pretty much ALWAYS delivers, I got chills when I saw Green Hill, Chemical Plant and Sky Sanctuary in HD along with their remastered sound tracks. Even seeing Speed Highway and City Escape brought back awesome memories (even though I still have both copies of Sonic Adventure for Dreamcast).
The story is actually quite interesting and it's fun seeing Sega poking fun at its past. Sonic and friends are celebrating his birthday when a monster appears out of no where and sucks all of Sonic's friends away from him. After every level, you rescue one of your friends.
The gameplay, while tighter than previous entries, is a bit harder to control than Colors was. I actually hated how they removed Sonic's ability to double jump, which would've made platforming much more precise rather than a useless slight boost forward (I cannot think of a single time that was useful for platforming). That alone caused a lot of frustrations for me.
Also I've noticed that while Sega used to have a real knack for making their games really difficult, Sonic games as of late hardly feel challenging, especially when you know if you keep on moving forward, you'll reach your goal, while Colors and Generations have added more platforming, I wish they'd add in more puzzles and challenges, kind of like Sonic Adventure did.
My main gripe with the game was the amount of content. It absolutely blew my mind to find out that the game only had 18 stages, I mean I had also gotten Super Mario 3D Land for my 3DS and that game had 80 stages and it's a handheld! Even Sonic Colors also had around 80 stages, platforming games in general should have no less than 30 stages (50 at least for a full retail game) and considering this is a game celebrating Sonic's history, they honestly had no excuse considering the vast amount of Sonic games they had access to, the 2 most famously left out being Sonic 3 and Sonic CD. Even the chaos emeralds were basically given to you, I remember having to work my butt off to get them and now they were just handed to me.
There were really just a ton of possibilities for Sega to truly put Sonic back on the top of the list of platforming games with this game but for some reason, they held back and gave us what pretty much is an incomplete game. My time with it was lots of fun, but it didn't last very long.
Story: 8/10
Visuals: 9.5/10
Sound: 9/10
Gameplay: 8.5/10
Value: 6/10
Overall: 7.5/10