I am an advocate of the Red Dot handgun sighting system, provided three things:
1. The shooter has proper and inalienable fundamentals.
2. The shooter regularly performs preventative maintenance on the sight system to avoid failure/damage.
3. The sight is co-witnessed with back up's in case of damage, malfunction.
It is the simplest thing in the world to teach someone that is new to shooting how to shoot with a red dot sight. The technology is remarkable. "Hold the weapon like I showed you. Put the dot where you want the bullet to go. If it doesn't go there, we'll work on your trigger-press." It truly is a superior sighting system in terms of simplicity, ease of use, and presentation.
Above all, the greatest success of any optical sighting system, in my oppinion, is that they allow the shooter to remain "Target-Focused". Properly lining up sights and taking a shot requires your focus on the Front Sight. We've all heard this a million times. Having a single-plane sight that does not pivot around the central axis of the weapon allows the shooter to line up their sight and fire without taking their focus off of the target. They are focusing THROUGH their weapon rather than ON their weapon. This, in my oppinion is one of the great victories of advanced optics and will be the future standard of sighting systems.
That is not to say that an RDS does not have it's drawbacks. Yes, it can fail. No they don't fail anymore than a properly-maintained handgun fails. Maintain your sight system on the same regimine you maintain your weapon. You will see instances of failure drop to 0. They are also bulky and proned to damage, (i.e. ejected shell contact). As the used materials become better, they become less bulky, the sighting technology becomes more efficient, and they become cheaper, we will see the gripes against them begin to fall away as they become more standard.
Just my two cents.