I saw this on Friday... it is quite impressive. Sure, the sound isn't the same as our IB's, but it is fantastic nonetheless. I was actually very impressed with the sound at the IMAX theater. I think this will be another must own for those looking to show off their IB's! The high quality 85' wide, 6 story tall screen really has a large impact on the exprience. And though the 3-D stuff was only about 20 minutes, it was pretty cool. I saw a fair amount of ghosting, but I had to sit in the 3rd row and off to the side. That taught me a valuable lesson... buy your tickets online before your go... that way you can pick a much better seat ahead of time.
My one and only IMAX viewing was Batman Begins. The bass was light and wimpy. We know from the DVD that it has some intense, deep bass so IMAX was the culprit.
Speaking of which, I was at an AES seminar about a year ago. There was a guy there from Delux studios who talked about the IMAX subwoofer system. He was very impressed with it because it used a "passive" subwoofer rather than the active subwoofer channel in Dolby 5.1 and DTS 5.1. He said the bass in IMAX is put in all channels and then passively crossed to the subwoofers resulting in a more natural sound than Dolby/DTS. His theory sounds like bullshit and in practice it resulted in pretty tame bass. Overall I found the spectral balance harsh and tilted towards the mid-range/treble due to the lack of deep bass to push the SPL's to the needed levels.