My vote: "A toy, not a tool"
I've watched several friends of mine use lasers, and they waste so much of their time waiting for the bouncing dot tell them when it's time to shoot, instead of using their natural instincts (and that was on a stationary target). I end up laughing and saying - "Stop chasing the dot and shoot for crying out loud!" Then for the heck of it, I spent some time practicing with a laser equipped gun too, and I was even worse than they were! At self defense distances, I believe that lasers are a counter-intuitive, delay inducing device, and a waste of money.
During the last few years, I've noticed that most of my friends who had installed lasers on their guns, seem to end up removing them, and then going back to using their natural shooting abilities -- unhindered by modern technology.
As for a few posts I've seen here ,about LEO's shooting around corners with mirrors and lasers, and the military use of lasers against moving vehicles? If it helps them do their job, then it's not my place to say otherwise. As for me, a civilian self-defense concealed carrier? I don't think any of those military & police situations pertain to my self defense needs, and I won't ever put a laser on my carry gun.
For play time at the range, yeah, they are a fun gadget, but nothing more.