Last night, I saw it again, this time at the IMAX theater (in Natick, Massachusetts, connected to Jordans Furniture) with dlanger and her son, E. It was in just two dimensions, but it was amazing. There is something about being in front of a screen so large that the edges are in your peripheral vision. I felt quite immersed. We were in the fourth row; all the seats behind us were full, when we got in just before it started. E said we were too close. They used a 70mm print, because the details were so sharp, in spite of the huge screen. I don't think they can do that with a digital or 35mm film release.
persis and T went instead to a contra dance in Concord. Persis hasn't seen HPatGoF at all yet; so no spoilers here.
At the IMAX theater, I used Etymotics earplugs, because it is so loud. Using those earplugs is the only way T would return to that theater at all. The earplugs have a little hole in their centers, and a filter in that hole, which permits you to understand speech clearly (or even run a mixing board) while wearing them, but 20dB quieter. You have to take them out to whisper, or the other movie patrons will be annoyed. We got four sets (for Persis, T, Diana and I) at the last (and probably final) Boston MacWorld; they cost $12 a pair online. This has been an unpaid commercial announcement from a very happy user.
A bonus attraction was IMAX 3D, including a preview (Polar Express) and a short subject. It's the polarized-lens 3D. They hand out polarized glasses on the way in, and collect them again on the way out. This is 3D done right. Sometimes the illusion broke down, because it was too close and moved too fast, but that was rare. They put stuff practically in your lap. I'd love to see Roger Rabbit in 3D.
I am definitely going back to the IMAX theater, even though it costs about 30% more than the regular cineplex.