I bought this to use in lieu of my military sleeping system. I'm 5'10" and 145lbs. My set up is this bag, a one-man tent, a half foam/half inflatable sleeping pad, a milsurp wool blanket, and disposable hand warmers in case I need heat in an emergency.The bag takes up almost a third of the space as my 2-bag military combo while being significantly more effective at keeping me warm. I took it out for a test run last night at about 5,400ft elevation with predicted temps overnight around 36°F. I stayed up till 0430 just to see how low the ambient temperature would get. It didn't quite get below freezing, only about 37°F, but I suspect the 23°F rating Snugpak claims is accurate, even for someone as scrawny as myself. I had no problems sleeping comfortably with my set up. Now, I will admit that I did have my wool blanket on top of me, but it was more for personal comfort. I was sleeping in less than I would normally have to wear with my old set up, which is great when clean, warm clothes to sleep in aren't an option. I got up once to go use the restroom and didn't have any issue gaining back the heat I lost from exiting.Being 5'10", I still had room at the footbox for the next day's shirt and pair of socks. As an unexpected bonus, the interior of the footbox is lined with a sturdier material than the rest of the bag, meaning you could sleep with your boots on and not worry about damaging the material.The hood of the bag wraps around my head quite comfortably with a drawstring and there weren't any rough surfaces or zippers rubbing my face.The zippers are a bit tricky to use, but for good reason. They're designed like genuine YKK locking zippers, meaning they will only open/close if you are directly pulling along the length of the zipper. This prevents them from easing open during the night, but it might mean a delay in exiting the bag in an emergency.The stuff sack keeps the whole thing in a small volume of space. It fits easily into the bag and cinches down without Herculean strength. I typically don't use stuff sacks as it's usually more effective to just stuff the item directly into whatever bag you're using, but it did make it possible to fit the bag in my motorcycle's saddlebag. It's always nice to limit the amount of things that are strapped to the outside of your kit.The space savings alone make this bag stand out to me the most. I could pack a liner and extra base layers with this bag and still have room for more in the space my old set up would have used. I slept comfortably without having to use my hand warmers and wasn't scrambling to start a campfire in the morning for warmth. Be sure to store the bag uncompressed to get the most longevity out of the bag.