I've been using lasers for some years now.
All my defense guns, handguns, rifles and shotguns, are equipped with (good) lasers. I wouldn't be without them.
I average practicing three evenings a week in low light/dark (home range).
I have compared and tested lasers and laser/lights against every other sighting system, night sights, etc. and IMO the laser is more accurate and faster than any other system.
Call Crimson Trace 800 442 2406 and ask for their free DVD, Shots in the Dark. They will also send you a free catalog. It's a must see.
The biggest problem with lasers is people try them or buy them and haven't a clue how to use them properly. There's a lot more to properly using a gun mounted laser than pushing a button. Just like with iron sights, it takes knowledge and practice to use them well. Many people, even experienced shooters, do poorly when first trying the laser.
On the other hand I've had brand new shooters immediately do unbelievably well with the laser.
A few pictures of laser use in low light/dark.
With a little practice you can do things that you probably can't do any other way.
With practice, at any distance, you can become as fast/faster with the laser in low light as you are with iron sights in daylight.
Laser in low light.
Iron sights in daylight.
Sighted in at about 25 yards the bullet strike will be close to center from arms length to forty plus yards.
Just playing around shooting a laser equipped Ruger Charger from the hip at 25 yards.
Soon as the weather gets a little better I want to see how well the Crimson Trace equipped S&W J Frame does at 50 and 100 yards.