The Crimson Trace laser is at least as reliable as the gun is. It will work every time if there are good batteries in it. In my experience, the less moving parts the more reliable the device. A laser has less moving parts than a gun. It's easier to check if a laser is working than to check if a gun is loaded, and we all do that all the time. I might be biased towards the technology, because I have more experience using laser pointers than guns. I have never had a misfire, FTF, or stovepipe in 12 years of using a laser pointer, but I've had at least one of each in less than six months of using guns. People put their lives in the hands of batteries all the time -- pacemakers, cars, cell phones.
As far as accuracy, I shoot a ragged hole at 15 feet with mine. Without it I'm not even close to that level of accuracy. The factory sights on mine are quite a ways off; the gun shoots significantly low and right. It is a much better gun with the laser than without. I'm pretty sure that even if the iron sights are dead on, I'd be much accurate with a laser.
Also when people are in live fire situations they tend to focus on the threat -- not their front site. A lot as been written on this. You can see it for yourself on numerous youtube videos. I'd much, much rather have a laser than take the chance that I'll be one of the vast majority that is too stressed to even use their iron sights. I practice with iron sights all the time on my other guns, but I'm faster and more accurate when the gun has a laser.
When I first started shooting I rented a sweet 686 with a CT laser on it. I was very accurate with the laser. Not so much with the iron sights when I turned it off. Now all the old timers will say, well you're a rookie and didn't know how to use the iron sights. That's my point. The laser was much more intuitive and easier to aim than the iron sights for a novice. When my life is on the line I want something that is intuitive and easy... not hard. Many folks that have a lot more training than I do revert to focusing on the threat when under fire -- easily seen on youtube.