This was the ultimate destination for Sonic from how it grew from the Sega Genesis and expanded its ideas with lore and characters and 3D gameplay, and this was the turning point. The game shipped in a rushed state, build-date the same month as the game came out and only a few hours of compile time between the review build and retail build of the game. And despite all that, it's a game that's so committed to its scope that it is a complete package, and only a few things were left on the cutting room floor. Using patches on Xbox 360 or PS3 the worst glitches can be alleviated and actually make Sonic's and Silver's gameplay decent. The level design is also fine, and conceptually the game has these "moments" that make you picture what Sonic Team was dreaming about. This is actually like the Sam Raimi Movie Spider-Man compared to the Animated Series cartoon, but it's Sonic, and this game. They clearly thought about all these movies that took old-school properties and made them look "realistic", and with Sonic it brings out a more visceral look and a more dramatic storyline that has a more emotive edge to it than previous games like Sonic Adventure 2. The music is fantastic and a lot of levels have a cinematic appeal to them like Kingdom Valley which ends with a fast-running segment through water falls that move in reverse due to a time-phenomenon that exists near an ancient laboratory of Soleanna Castle. That's part of the story concept too, to have this time-travel plot about the wish to move backwards in time to be able to "save those you love", and another feature that gives the product a poetic edge.
What you're left with is a broken game that is so earnest in what it wanted to do, that you can't help but feel a little sorry for it, and it's a shame that the fiasco of its original release made Sega shy of ever letting people play an updated version of it. Fans have already patched the console ports, and Sega once promised a PC release that never came to be.