Longer reach for the hammer, shorter space between the grip frame and trigger gaurd (lotta shooters complain about getting "bit" by the T-gaurd under recoil), they don't play well with black powder, and they're just not that readily available. Mostly though, I think it's just because the grip frame is "different" and you either like...or you don't. Most don't like it as well, those that do REALLY like it.
I like em!!!!