Outdoor Research Basic Bivy
OR markets this as a simple yet usable and reliable…
Design: bivy sack without poles or hoops
Ease of Setup: none, toss it on the ground
Weight: 1 lb 4 oz
Price Paid: $189
OR markets this as a simple yet usable and reliable shelter. I agree that it is both. Only real downside (other than the ones you should expect like limited ventilation and not much room) is weight. There are lighter products out there, but at 20 oz., for something that could be very liberally construed as a 4 season tent, it isn't that bad.
I bought this to have a bivy capable of use as a standalone shelter, it is. Like virtually every bivy, I've ever heard of, generating condensation inside is easy, but I haven't experienced any excessive, and generally keep my face out of the bivy or the flap fully open.
Entry and exit is easier than you would think with a little practice. I hold it up and drop my sleeping bag in while holding onto the bag hood. There is enough room for a pad inside, but I usually leave it outside. I use a kite weight Tyvek ground cloth, but you could use it directly on the ground. The mesh works well and has a separate zipper from the bag. Some people don't like having fabric right on their head/face, but it really doesn't bother me. I have never completely closed the Gore-tex even in a hard rainstorm, but the zipper design allows you to minimize the opening on one side to help avoid leaks and the storm flap is functional. The head end only opening increases weatherproofness and decreases weight.
I like having more flexibility on bivouac site than possible with a tent or tarp and the ability to readily take advantage of natural shelter augmentation (boulders, overhangs, trees, etc.) Some times, I'm just too dang tired to think about pitching a tent...let alone carrying it. This puppy really is waterproof even in steady rain although the claustrophobia and noise of raindrops when you batten down the hatches cannot be described, only experienced.
Bottom line, this is a minimalist shelter that will better connect you with the environment, allow you to go from stargazing to rain protection without moving, add a few degrees of warmth to your bag and maybe even save your life if you are caught out in bad conditions with nothing else. One of my favorite pieces of gear.