I own the Mystic and use it for winter trips here in Tennessee. I am a big guy and typical bags won't begin to work with my 54 inch (135 cm) chest. I like the sleeve in the bottom which holds the pad in place - it prevents me from rolling off in the middle of the nice. The pillow is also especially appreciated.
The biggest downside side is its poorly stated weight. My Mystic, which lists at 2 lbs, 4 oz, actually weighs 2 lbs, 11 oz, a 19% error. Every BA bag I have looked at is comparably understated for weight. However, the only other companies I know of which will fit me are Montbell and Western Mountaineering, both of which are outside my price range.