Another Big Agnes Seed House (SL2) user. I've toured and back packed with mine extensively, in all kinds of conditions.
For some reason it is often on sale, and I think at the sale price it is a great deal. I think I paid just under $200 for it in 2008.
Pros: Light, very fast to set up, very airy so condensation is rarely an issue. Seems pretty durable so far. Spacious for one person + gear. I did the Sierra High Route with it and was very very happy.
Cons: Because it's open, it is really a 2.5 season tent. It handles wind very well, but if you are wind+snow, you're going to be unhappy (speaking from experience here). With misty sort of rain or heavy rain + wind, it's possible to get moisture coming into the tent from under the fly. You really have to stake out the fly properly to not get condensation and to have it handle wind properly -- which is a small extra hassle. Tight fit for two people.