Many people love the Aimpoint b/c it is a super rugged, super simple, super quick optic to use. However, some people do not like that it is battery dependant and you have to turn it on.
For those people who did not want to rely on batteries, and have a optic that is always on, they went the Reflex route. A lot of people really loved the Reflex's triangle reticle as well. You can use this tip for making accurate shots out at greater distances, while maintining a big reticle that is VERY quick to place on target for CQB. Dot reticles lack the size and tip for increased accuracy potential at distances.
Reflex is another great optic. Super rugged, super simple, super fast. But having it depend soley on tritium and fiber optics lead to some problems with the reticle washing out. In addition, the triangle is some times too big and solid and can cover too much of your target if you have to hold over for bullet drop.
The Tri-power
seems like it is the best of all worlds in that it is not battery dependant, and is always on. Yet it does have a battery back up for the times when an old Reflex would have washed out.
It also has a Chevron reticle, which is much like an upside down "V". It maintains the large size of the triangle, which is awesome for CQB, maintains the tip, which is great for longer shots, but hollows out the bottom so it wont cover up more of the target than is necessesary. In addition, they made the reticle useful for range estimation. Width of the bottom outside edges is the same width as a average human torso at 100 yards. Width of the insdide of the V is the same as the width of a human torso at 200 yards.
This thing is has a lot going for it and a lot of us are super EAGER to get our hands on it and see if it is everything we are hyping it up to be! Anyway, at least these are some reasons why I am so eager to see it.