I used the BPIAB two weeks ago for my son's birth. I *loved* it! I did use the seat once or twice when my MW was checking the baby's heartones, though I probably didn't need to. It didn't get fully enough inflated, so it wasn't as supportive as I would've needed. I spent most of my time either fully submerged (the depth was wonderful!!) sitting on the floor of the pool, or during ctxs I was up on my knees in one way or another. I did rest my arms on the cushion, too, but again it wasn't quite inflated enough or that would've been really nice.
I definitely loved the pool, but the best thing was the size of it and the depth!!