It's free-standing, easy to set up, roomy, relatively waterproof, and durable. The one thing I don't like about it is it's somewhat heavy. I have always used it for bike touring and other types of camping where I wasn't actually lugging the thing around over long distances. It weighs in at 4 lbs with all the parts. That's about twice what a modern lightweight one-man tent would weigh. So I think I'm going for another option.
I also have an Outdoor Research Basic Bivy. I have used it before on a bike trip and it seems to work OK. For those who don't know, a bivy is basically a waterproof sack that you put yourself and your sleeping bag into and zip it closed (think fancy body bag). The OR bivy gives you the option of just zipping the bug screen if you want to breathe a little, or zipping the whole thing closed if it's pouring rain and breathing becomes less important.
I liked using the bivy, but the time I used it, it was pouring rain and you can't store gear in there and there's no room to sit up and stay dry at the same time. So I purchased an Equinox Egret 8x10 tarp that I will carry along with the bivy. That way I can set up the tarp in any number of configurations (see video below for an entertaining demo) and use the bivy inside the tarp if I need bug protection or extra warmth.
I got the tarp in the mail today. It looks pretty nice, ripstop material of some sort that looks coated and waterproof. The 8x10 version weighs 1 lb 11 oz, a lot lighter than my tent. The bivy weighs 1 lb 3 oz, so together I'm still lighter than the tent option. I still have to add the weight of some stakes and 550 cord but I think I'll still be about a pound below the tent.
I plan on setting up the tarp sometime this weekend. I'll take some pictures and let you all know how it turns out.