You know what I've noticed about the first five 3D Sonic games on consoles? It's that they seemed to have decreased in quality until Sonic Unleashed rolled around. Allow me to explain the quality change of Sonic Adventure - Sonic 06. I don't count Sonic Riders in the list.

When Sonic Adventure burst onto the scene on the SEGA Dreamcast, most owners of the system set their sights on getting the game. When they got it, most people rather enjoyed the game, mostly for Sonic, Tails, and Knuckles' gameplay.

Then Sonic Adventure 2 rolled around a couple years later. This game mostly got the same reaction that SA1 did. However, there were some things in the game that gamers weren't really fans of, like the butchered treasure hunting stages.

Then, SEGA jumped into the third-party group of gaming and released their next game, Sonic Heroes, on the Gamecube, PS2, and Xbox. This is where Sonic started to take a turn downhill. In my opinion, the game was just simply 'meh.'

Then, disaster struck with Shadow the Hedgehog and Sonic 06. Both failed miserably and, as a result, damaged Sonic's reputation. Badly. However, in my opinion, Shadow is the worse of the two. If it's not the terrible missions and non-canon endings that do it, it's the godawful overall design of the game.