COLD

20 degrees my butt. I wouldn't take this thing out if the forecast threatens to drop below 40. I carried this bag out for a few nights of 30 degree weather, and I was supremely disappointed. I nearly froze to death in the bag; all while wearing two layers of fleece, two pair of socks, and a thick hat, too.
The short zipper is annoying, too - it only goes halfway down to the feet. It also has tendency to unzip itself if you're not careful. There's no draft collar near the neck. The bag is not very breathable - leading to a very clammy feeling bag in the morning. The bag also feels suspiciously thin, leading to a rather uncomfortable sleep without a thick sleeping pad.

On the good side, it does seem well made. It has a comfortable shape for a mummy bag. It stuffs down fairly small (although still larger than my much warmer down bags) and seems pretty light. And wasn't too expensive.