Changed the game
My old bag was a Marmot Sawtooth 15. That bag got great reviews and was warm enough I guess, but it just didn't compare to the WM UltraLite. The Marmot weighed nearly twice as much as this thing. This bag has brought my base weight down to under 8lbs, and I can absolutely notice a difference. I don't even have to use my hip belt on shorter trips, my bag is so light now.
Other than weight, another great thing about Western Mountaineering is that their temperature ratings seem to be very accurate. I had used my Marmot bag in 20 degree weather before and was uncomfortably chilly in the morning. It got to about 25 where I was this past weekend and I was still extremely toasty, leaving me no doubt that this bag will go to at least its rated temp, if not even lower without problems.