I guess they're OK. For me they're just something to have to fool with, and hope they work when they need to. Dropping a pistol on concrete could be a problem. Dropping one in snow, or mud could be a big problem. Using one in heavy snow falling, or rain on the lens could be a big problem with sighting.
I've always viewed a pistol as a close in fighting weapon, and I know from personal experience, others experience, that the first shot off usually wins, whether it hits anything or not.
Like I said: I don't have anything against'em, I'll just stick with what I know works, regardless of the weather, or battery life. I do like the Sig flashlight on my pistol, but if it quits working, the pistol sights don't. ]