If you're looking at the Moonlight version,I'd recommend you check out the Ultralight Bivy at borahgear.com. Lighter, cheaper, well reviewed, excellent personal support, and made-to-order here in the USA for those of you that appreciate that sort of thing. I think mass drop previously offered a version it that sold out fast. These Terra Nova bivys seem like a reasonable deal. Like the Borah Gear product, I probably wouldn't use them as a stand-alone shelter when rain is in the forecast, but they pair nicely with a tarp.
CPT_RedBeardI have the side zip for ease of entry/exit. Loop sewn into the center of the bug netting section allows you to elevate it off your face (I use a small segment of light elastic shock cord and connect it up to my trekking pole in the shelter). Here's my set-up with the Borah Gear bivy + tarp, a cheap mylar ground cloth, Lawson cord, pad & mass drop/EE quilt in the bivy:
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And I still think both of the bivies on this drop would work well in a similar set-up (and they're well priced).