Rating: 4 / 5
This review is for the large bivy with the old-style bug headnet (a mesh headnet bag sewn across the chest, pulled over the head, under the bivy).
This is the best value hands down in water resistant ultralight bivies, ranging depending on options from $40 to $70.
Sizing: I am 6'3", roughly 150 lbs and while the width of the basic bivy was roomy for me, my Gossamer Gear nightlight 3/4 pad, and my Jacks'R'Better No Sniveller, the length is a bit tight. This is not a problem when not using any hood, or when using the bug hood, but using the fabric hood pulls tension into the bivy and compresses loft at the foot of my quilt.
Headnet: The old headnet design creates a roomy bug tent over my head when suspended from a tarp, pole, or branch, but requires spare clothing or shoes to close the sides of the mesh off.
Fabric. The 1.3 oz silnylon floor proved durable through about 12 nights of use this season, but is slippery when using inflatable pads.
The 1.1 oz DWR fabric has proved breathable - I have not experienced condensation inside (Sierra Nevada conditions, never fully closed bivy).
The DWR treatment stood up to a direct light rain for roughly 20 minutes when I did not set up a tarp, which I think is about all you can ask from a not-fully-waterproof fabric.
Recomendations: Because the new design takes care of the headnet closure issue (see www.titaniumgoat.com for details), my only recomendations would be to make the large size larger for tall folks like me, and to change the color scheme (nitpick, I like the green top, but purple floor is kinda funky).