Okay. Here's mine.
Sonic Adventure 2:
Let's see. I hate the story. You're given the option to be good or bad but it all ultimately ends up good. Treasure hunting gameplay was crap. In Sonic Adventure, it gave you opportunities to explore stages you've already played through as Sonic in new and exciting ways. The stage design made specifically for treasure hunting was confusing and flat out bad. Lastly, the music. Specifically the music with lyrics. I don't mean the game's theme songs made for all of the characters. I mean the City Escape and every Knuckles stage. I don't mind hip-hop type music, I just hate the lyrics. They're terrible.
Sonic '06:
I really wouldn't mind this game if it hadn't destroyed Sonic's reputation.
Sonic and the Black Knight:
There's alot I don't like. I'd rather not waste my time writing it all.
http://www.gamespot.com/wii/adventure/sonicandtheblackknight/player_review.html?id=655064&tag=contributions;review1