First impression: I'm deaf in that thing. And I have tunnel vision.
We did a lot of kirikaeshi, which amounts to organized hitting each other in the head -- or, sometimes, in the side, and occasionally on the wrist. After some initial confusion on my part, I got into the groove and was no longer trying to move when I wasn't supposed to, or vice versa.
After today, I have a new appreciation for what a thrilling experience trying to fight in heavy armor must have been, just purely on the level of being unable to see or hear anything around you.