I have laser grips for both of my carry revolvers: an SP-101 and a 642.
You need to have good trigger control, even with a laser -- keep that dot in the same place before, during and after the trigger pull.
I have a 5-spot target in my basement where I practice dry-firing with these grips. Keeping the laser dot in the bullseye while shooting is difficult with heavy double-action trigger pulls, but it's doable and it's great practice! For the price of a case of practice ammo, you can have a pair of these grips and improve your skill for the rest of your life, at home.
Some say that lasers don't replace the sights. No, they don't, but my fixed sights are still there -- I didn't grind them off when I installed the CTCs, and I still practice shooting and dry-firing with the fixed sights.
Some say the laser will give away your location. I'm not a soldier, an assassin, or a LEO, so giving away my location is not a worry of mine. If I'm under attack, the assailant already knows where I am. If someone breaks into my home, I prefer that they quickly learn that I am there and am armed.
A laser won't improve the inherent accuracy of your gun, of course. But it can drastically improve your accuracy when shooting from all positions other than a normal shooting position.
Bottom line is that they serve a purpose and, for that purpose, they're great.