Really really rate this bag. I have used it in deepest winter and it hasnt failed me.
Its versatile in that you can use it as a semi quilt or a bag and also its adjustable to fit around you and your mat.
Dont forget that no matter how good the bag you need a decent mat underneath or it will feel cold.
Its light, warm, adjustable, comfy.
whats not to like

Since this quilt is new to me I haven't had the chance to push it to its limits yet. But, it has been used down to the low 30's and is toasty, at 20 degrees it might be pushing this quilt for me as I'm a cold sleeper and love lots more insulation then I really need, wearing extra cloths works for me. The nylon taffeta used on the inside feels soooo much like silk it's like sleeping at a 4 star hotel in the middle of the wilds, and the views are so much better. I have yet to sweat out the down or have the bag exposed to more than a slight drizzle but so far the quilt has stayed dry and the very little dampness from normal sleep dries up within minutes of flipping the bag inside out in the morning. This quilt also cuts about a pound and a half from my comparable sleeping bag and packs much smaller, about the size of a 2 liter bottle without the neck. I have used a spray bottle on the Pertex Endurance parts and the water beads up and rolls off easily so I'd trust this quilt in a tarp in most weather except possibly torrential downpours where I'd be using a bivy sack anyways. The loft is between 2.5" and 3" so it's 20 degree rating is pretty close to spot on depending on your personal biological heat engine.

So far I have no dislikes about this quilt. It works with many different sizes and shapes of sleeping pads and the eyelets for the sleeping pad straps work brilliantly- when I turn in my sleep the eyelets slide along the straps so no airways open up to chill me awake. I've even taken to using it at home as it is far more indulgent then my normal quilt. Only one wish though, it would be nice if it had a cinch closed foot box to help heat regulation a bit more and allow for more uses around the campsite. All in all this is now my favorite sleeping bag/quilt and absolutely brilliant when used in a hammock or on the ground. This quilt will get a five star rating if it's still doing its job well in a few years but for now it's a close to a five as I've yet encountered. Light, packs small, toasty warm, easily adjustable, feels so good against the skin, normal dampness dries quickly so what more could you ask for? Okay it would be nice if 800 down were cheaper but at this price compared to comparable rated sleeping bags it's close to half the cost anyway, so pony up the baksheesh and sleep like a king/queen while everyone else is still cursing the weight and zippers of their traditional sleeping bags.

At 19 oz this thing is light but the 20*F rating is off by 10-15 degrees. The Ultra 20 only keeps you cool not warm at 25*F with softshell pants, TNF Impulse Hoodie (hood on), wool socks and beanie on. Compared to my Golite Feather 20* bag with the same clothes minus the hood on the hoodie and the beanie I can go to 13*F and be toasty warm. I was useing a montbell ul 90 and GG 3/8" CCF pad in both cases. This quilt is more a 30/35* rated quilt. Stitch quality is poor as well. Found several loose threads on both edges and down coming out. The plastic loops look and feel very fragile as well. The straps are way too long as well. The shape and size are great for great coverage that keeps drafts at bay. The loft is just lacking for the 20*F rating.

This quilt comes with thin straps that go around your sleeping pad. The quilt has small plastic slots sewn to the edges that slide on the upper sleeping pad strap allowing the edges of the quilt to be tucked in tight when its cold or spread out when its warm. When I tried this set up at home the first time I rolled over one of the plastic slots tore out of the seam. The plastic pieces need to be stitched better if used as intended. Instead, I cut off the plastic slots and sewed a strip of 0.8 oz. nylon, 6 to 10 inches wide, down both edges. The nylon strips are tucked under me when its cold and spread out when its warm. This eliminates cold drafts when turning at night and makes the quilt warmer. I find no need to attach the quilt to my sleeping pad. The nylon strips add a total of one ounce to the quilt after removing the plastic pieces and the sleeping pad straps.

I was skeptical at first on how well the Ultra 20 would last in cold weather after hearing mixed reviews. I recently bought this quilt from this site and tried it in Yosemite. It got down to freezing temperatures and I woke up with frost on my bivy sack. Surprisingly I was quite warm for the most part, but my toes were a little cold. This was due to not changing my socks before going to sleep and the perspiration around my feet rapidly cooling (my fault). I was wearing most of my warm clothing to sleep, which is what you're supposed to do with a quilt like this, and it worked quite well. The Ultra 20 is super light and when used correctly will keep you warm at night. Another great product from GoLite.

Used it out in the desert last weekend. Temperatures were in the low 30's and I didn't feel cold at all. It worked very well with my Therm-a-rest Prolite 4 (regular) mattress. One concern was how the straps would work and how durable they would be. So far no problems at all. I keep the "clamp" or "buckle" part of the straps near the bags eyelets. This makes it easy to adjust and get out of the bag. The amount of room it allows all depends on how tight you have the straps tightened. Another concern was not having a "hood" to put my head in for warmth like a mummy bag typically provides. I didn't have a problem there either as my head was never cold. If my head did get cold, I would just put on a ski cap and problem solved. One thing I did learn is not to put the sleeping pad into the lower portion where you feet are "cocooned." You'll have too much tension and could possibly rip the sleeping bag. Keep that portion above the pad and you'll be fine. Great product and I highly recommend it.

Location: Mt. Whitney
Usage: bivy
I had the ULTRA bottomless bag wrapped over a Thermorest Full length inflatable pad. Then have a bivy sack over everything. I can sleep on my side and enjoy the freedom of changing positions.

It was too warm as the temperature was 40F.

Just used this bag for the first time in the Pecos Wilderness and I was cold in the 40 degree nights at 12,000 feet - even when wearing my fleece jacket, capilene long johns, etc. True, it was damp outside and I was just under a tarp.... But even though the bag stayed totally dry, I was cold.... Since I am usually in warmer weather, I will keep this VERY light top bag but will add a fabric bottom to it for ease of use. I didn't like the straps, which kept sliding around under the pad whenever I moved.

The light weight and reasonable price are unreal & it translates into poor performance. I've tried this bag in the 30 degree range a few times and it was really cold. Very disappointed with this bag. I plan on going with a Montbell UL SS Downhugger #1 & using this bag over it to bring it to sub-zero ratings. Lesson learned is that it's worth spending the cash for the right stuff. Would avoid this bag if you're looking for an "all around" bag unless you plan on using it for 45 degrees or warmer.