I have only used this shelter in the field for a two day trip, so that is all I have to go on...
My main attractions to this style of shelter were the weight to space ratio, and to the Origami specifically, the price (I paid $111). I looked at a similar shelter called the Trailstar made by a company called Mountain Laurel Designs, which is lighter (by nearly a pound) but those weight savings are accomplished through a compromise on the ease of entry; the Trailstar must be propped up on one side to get in, versus easy zipper entry. The Trailstar also would have cost me ~$35 dollars more.
I'm too cheap to buy adjustable trekking poles so I was stuck carrying the included adjustable pole, the lightweight ski poles I use are only 45" tall and that just wasn't quite enough to set up the tent properly and have an adequately comfortable space for two people and two dogs (medium sized dogs: Sheltie/Australian Shepherd mix). One thing I have not figured out is whether the listed weight includes the pole; with most tents it usually does, but I'm not sure with this one (I'm too cheap to buy a scale). Setup does take some practice; I have done it 5 times and still have not mastered it. One of those times was out in the backcountry trying to suspend it between two trees. Though it can be done and probably with some practice it can be done well, I did not find this to be a very practical method. If you can master it, it would save some weight and open up that space in the middle (possibly for another person, or just to allow you and your hiking partner to cuddle, if you so desire).
I was somewhat worried about bugs with the open design, but camping at about 8500 feet in central Colorado mid-August, I had no problems. The only other issue I had with the open design was with my dogs. I attached their leashes to the center pole and that was enough to keep them in the tent through the night, but it did not prevent them from a seemingly endless curiosity about what was going on outside the tent, and with just enough space for them to stick their heads out, this was a problem that interfered with sleep. The solution I'm working on is a curtain of no-see-um mesh to hang around the perimeter which will act as a visual deterrent and a little extra bug protection, while maintaining crucial ventilation, and only adding a few ounces of weight.
We did experience some light rain while we had the tent set up between the two trees and though there was no problem with water getting in, there was one point where water managed to gather on the bottom edge of the tent (I could not get the cord I was using (a couple of the included guy lines) taught enough to hold the tent up properly once I staked it out (it will take some practice and perhaps a different type of cord with less elasticity). As far as moisture in the tent, I had no problem with that, leaving about a 2-3 inch gap between the edge and the ground seemed to allow plenty of ventilation and it breathed much better than my last tent (single wall Eureka Zeus 2).
Well, I hope I have covered the important issues. Overall I think this is a good shelter but it really comes down to individual needs/preferences. If you like the security of at least one layer of mesh or sil-nylon between you and nature than this is not the tent for you. It is a good choice if you are trying to transition from heavier fully enclosed tent style to lightweight open floor tarps though. I would not pay the MSRP of $175 or whatever it is, you ought to be able to find it cheaper than that on here or Google shopping, I was not willing to pay more than $125, and I think that is about the most it is worth, otherwise I would pay a little more for something like a Golite Shangri-la 3 or Black Diamond Megalight or something like that. Well, I'm not sure how these reviews work, but if possible feel free to ask me any other questions about the Sierra Designs Origami 2 and hopefully I can help you. I hope this helps you make your decision!
Click Here to see more reviews about:
Sierra Designs Origami 2 Person Ultralight ShelterProduct Description: Origami tarps are everything from a full-coverage backpacking shelter to an airy sunshade for a day on the beach. Multiple guy-out and stake-out points allow you to pitch in a variety of configurations to withstand gusty winds and adapt to changing climatic conditions. Designed from five equilateral triangles with a full-length zipper down one seam, any side can be staked at ground level for more coverage, or tied up for easy access or for lots of ventilation.
Buy cheap Sierra Designs Origami 2 Person Ultralight Shelter now Get 28% OFF
It's a mixed blessing. I bought it instead of a one man tent, b/c I wanted: 
