I have heard nothing but good things about CT lasers. They only bad things I have heard are that they make the grip feel to thick and that it would give away your position at night if you has to draw. But as far as the laser it self, it works
I have this same laser on my G19 and am not entirely impressed...yes it works as advertised, but racking the slide is harder, and my thumb gets jammed at times when I am moving quickly. Also I like the fact that the laser is automatic in it's operation, but I can envision times when I don't want to be given away by a big red laser beam swinging around dark spaces and giving me away. I would like an override switch so I can shut it off at times...but that is just me.
I have Crimson Trace Grip Lasers on my Colt 1911, & a S&W 629. On the Pro side: Thew work well in darkness, or reduced light, hold zero fairly well, are easy on batteries, & generally do as they are advertised. The Con side: Pretty much useless in bright daylight outside, if you do have to adjust them the allen heads for windage & elevation are super small & care must be used not to strip them accidentally, they are not "Mil Spec" in regard to being waterproof, so it's anybody's guess how much moisture, for how long a period, might have an negative effect of their performance. The laser lens can get dusty, or dirty, but are easily cleaned up with a q- tip.
I have a Viridian X5L Gen 2 laser/tac light mounted on my G21 Gen4. It has 6 functions, Laser only, Light only, Light & Laser together, Light on an adjustable strobe, Laser on an adjustable intermittent pulse, Light on adjustable strobe w laser. The Tac light is very bright for it's size, about 160 lumens. The green laser is vey bright at night, and it is possible to use it in daylight. The controls are simple to operate with either fore finger, and when turned back on the unit will start in whatever mode it was shut down in. It takes a CR-123 non rechargeable lithium battery which is a drawback if you use it very much. And it isn't Mil-Spec in regard to being waterproof either, so outside in a downpour wouldn't be a good idea. It's a nice unit for my purposes, inside at night, or outside to do yard checks. It really adds to the bulk of the G21 though, and makes it pretty much a home defense gun, which is fine with me. They are more expensive than crimson trace, but they do more too.
Probably the most useful function of the lasers is dry firing exercises. They don't lie. You may think your rock steady on your trigger squeeze, but turn on the laser, and you'll find out your not all that, when the little dot of light just won't stay put. It can be humbling. They aren't a substitute for good marksmanship of course, but they can be useful from time to time.
My friend has the crimson trace laser grip.. I wasn't keen on the grip after it was added. But it does the job, don't have to think about switching it on at critical moments.
I watched the crimson trace CD, that they have. They teach you some tips on how to use the laser grip. During indoor or low lighting situations, to prevent giving your location away whilst gripping the gun you can put your trigger finger raised in front of the laser's line of sight to block its projection. And when you are ready to fire you place your finger onto the trigger hence exposing the laser onto the target. Gets some getting used to. But it does help in hiding your location when using it.
I have the crimson trace rail master on my G19.. Nice..it has a on and off switch, which is manually controlled . But now I can't find a holster that fits the rail master.
One last thing, I got the laser mainly to help me practice when i first got into shooting. And dry firing. It really showed me my pain points like flinching and my anticipation of the bang.. I see the laser bounce around. It helped me to be consistent and stay steady. And correct my flaws. That's why I got one. But I guess its not every ones cup of tea.
Its nice to have, but I mainly practice on the iron sights now since I got myself up to a competent level..