Dad's got one in .45 LC that I've shot quite a bit, and my experiences are about like Rod's-- With stout 270g loads, it's a handful, with that smaller butt and grip area. But very nice to carry. Dad's came with a very hard DA pull, but it was hard and smooth, which allowed me to make surprisingly tight groups, firing offhand, D.A. at 10 yards (all nearly touching). I was impressed. S.A., it was okay, but nothing really special. (That's not what the pistol was designed for, so I didn't put a lot into S.A. shooting or from the bench.
Actually, the Mountain Gun is pretty dadgum stout-- it's no pipsqueak in the topstrap or the front lug-- it weighs about 30 oz, if memory serves (unloaded)). The main thing that makes it so packable is its smaller frame in the butt area. If it were mine, I'd lighten the trigger a tad, but it's great out of the box.