I started shooting as a kid with a couple single action 22's. My first centerfires were also single actions. I moved on to DA revolvers and some autos, but for some reason have never been able to shoot an auto as well as a revolver, even an SA revolver. For fun, and because I tend to carry an SA Ruger quite a lot where I live (sort of rural-ish, with bears and stuff around), I shot a some plate shoots with a Ruger 45 SA. My scores were about the same as with a Smith model 19, and a little better than with a 1911. No, they aren't the best choice for defensive use, but one is hardly unarmed with one. Reloading them will never be as quick as a DA revolver, but not quite as slow as most seem to feel.
As Nyeti said, if one is used to them, they aren't all bad.