I agree with Daisy. I used a bivy and tarp combo that weighed about 3 pounds, and loved it for the same reasons she did: it was lighter than any tent available at the time, I could use the bivy alone on nice nights and fall asleep watching the stars, and combined with the tarp in the rain, I had bombproof protection.

I quit using it when solo tents (specifically, the MSR Hubba) came out. For the same 3 pound weight, I had just as much floor space, more headroom, and (since the tent wallls were nearly 100% mesh) could still fall asleep looking at stars on a nice night. The vestibule created by the fly gave me the same amount of extra living space in the rain as the tarp did - enough to cook in, and keep my gear dry.

The tent cost less, actually, than the Integral Designs bivy and tarp I had been using - so, faced with the choice today, a mesh-walled solo tent wins on nearly all counts.