I had seen another review before purchasing that complained of the inside fabric, so that was my only initial concern. After camping with these, my husband and I had totally different reactions to the bags (we used them as singles, not zipped together). I think they're wonderful. The inside feels like high quality cotton/poly sheets to me, and the bag is REALLY warm. My husband felt strangled in it and it kept twisting around him. I think the difference was his sleepwear that didn't slide against the inside fabric.