My buddy got one of the internal laser sights. This gun is is first, and so far only, firearm. He put it on there, IMO, because he had too much money and wanted every little bell and whistle for his gun.
While he saw a quick jump in his accuracy, IMO it's more of a crutch than anything. The rest of us, who got into pistol shooting at approximately the same time (a bunch of friends took a CCW course together), are much better shots than he is. If he doesn't have that sight, he can't hit the broad side of a barn.
The only advantage that I noticed was that it helped us address some shooting technique issues. Observers could watch the laser and easily see if the shooter was pulling to one side, overcompensating for recoil, tensing up, etc.