Ok, I always wanted one but didn't want to cough up the ~$300 they go for. I currently use a Coleman Exponent Inyo 2 (two person) that packs at about 5lbs for only about $100. I suck it up and carry the extra weight, because I like the room (me, my pack, etc, inside during bad weather.) I also have an MSR Microzoid that packs at about 2.5 lbs, but let me tell you, you have to crawl outside to change your mind (and your underwear, but that's another story!).
But REI just ran a sale on the Hubba Hubba for about $80 off, and I had about $50 in my REI "dividends" account. So the time was right.
Now, the Hubba Hubba also packs at about 5lbs, but unlike the Coleman Inyo 2, it's square AND free-standing.
Right now it's "camping" upstairs in the gameroom waiting for a field test. Let you know how it turns out.