Great to have! Not sure how cold it will be good for, but it's a good design idea-wise for a few reasons:First off, there's the mosquito net. This is an excellent idea, because if you're trying to get some sleep, the bugs can be a major problem (they don't show that in any of the Rambo-type movies). It unzips, but doesn't zip off all the way- there's a little tab where it stays connected. Don't know if this is better than it zipping off completely, but it's not a bad thing on its own (if it got a hole, it would be hard to repair- maybe mosquito netting taped or glued on over the hole?).Then there's the zippers on the bottom AND side of the bag. There's a lot of benefit in this type of design. For one, you can unzip it & fold it around yourself like a blanket (which lets you jump right out of it if you're sleeping with your feet sticking out or to wear it over yourself kind of like a cloak). For another, you can unzip the bottom zipper & slide it over a hammock like a sleeve so it doesn't get crushed-down by your weight (it's all outside over everything, kind of capped-over). Usually, you'd need to put a stick or a pen through the teeth of the zipper on the bottom & open it up to do that- then you'd probably have to pull that section apart with your hands after you unzip everything to get it to zip-up right again (because it might leave that section closed whereas the longer part is open). There's a corner that isn't zipped when everything is fully zipped-up, but it's kind of blocked by a flap & it's very small (a knotted sock would actually be pretty hard to thread through it, but it's an option).Packs down very small (smaller than a football, no matter which kind that means to you). It's actually about the size of a hero sandwich, to give you an idea. MIGHT be able to put it in an outside pocket of an ALICE pack or in one of those water bottle carriers or even rolled into a shemagh/kerchief that's tied around the waist.Seems fairly durable & water-repellent, but a bivy can always be used. Actually, one of those SOL bivies that are like a space blanket slipped over the bag might make it good in very cold weather (meaning "cold enough to snow & below"). I'd like if it was better for that kind of weather on its own, but it's good as is & those SOL bivies aren't too big (actually, they can fit in a large coat pocket like the black garbage bags that people carry for makeshift always-have-it rain gear).