Like I said, It's my first swag and yes I did feel claustrophobic on the first night using it, Perhaps because I'm so use to tents.
I've got a kind of funny story though, I had it under a tarp because I was expecting rain, Just as I was dozing off, the wind picked up, the tarp came loose and flapped around at my feet. I totally lost it and practically sh@t myself, I screamed loud enough to wake up the other people I was camping with. After realising what was happening, I was sooo embarrassed.
As for comfort, It has a dual density foam mattress, (heavy duty foam up the torso half) i was suprised on how comfortable it is. I woke up with sore hips from sleeping on my side, but a stretcher, self inflating mattress (or a tea spoon of concrete) should sort that out. I'm sure having no pillow didn't help.