All I can say is that most of the Imax footage was the scene in the forest where Optimus takes on 5 enemies. It looked amazing on my 46" LCD!! I thought I would miss it, but it as soon as it switched to full screen, I noticed. I didn't see anything before this scene and doubt I will after, b/c this probably did clock in at 2 mins, or even more.
I'm not a huge transfer guy, so I can't get into any technical aspects, but I can tell the audio is a bit lower than the first Transformers BD during dialog scenes.
EDIT: More Imax footage when Devaastator forms!!!