I don't know about SSMB in particular but I remember a lot about what it was like. A lot of hatred and boiled piss when it came out. A lot of excitement before it was released... and then increasing concerns the more we learned about it. Like the design aesthetic was beautiful but seeing Eggman's design and Princess Elise was... odd. I remember not having a 360 at the time and being jealous when it was revealed there were 9 playable characters. I also remember being a bit confused by Blaze being there. I hadn't played Rush but I did know that she was from another dimension. Also, Sonic Rivals was being promoted at the exact same time 06 was being promoted so I remember one guy saying we didn't have to worry about Silver's speed in 06 because he ran super fast in Rivals, not yet realizing that the how fast the characters are is dependant on the game that they're in and not the character themselves.
So that's all I got.