I have killed better than 2 dozen birds using the original holosight and the holosight II

The dot in the circle reticle makes for a great "circle of death" for turkeys

Batterries will work for three weeks straight of every day hunting. Good idea to keep fresh pair of batteries in your vest. Holosight does flash the reticle for few seconds when you turn it on, and the batteries are getting low. As to changing intesity settings, not a big deal, unless you don't pay attention to it. I adjust mine usually once after the sun clears the tree line, and again if it gets real bright out. Red dot scopes have similiar issues. I would expect auto light compensating red dot scopes in the future, one less thing to worry about.

Your eyes do better at centering things in the circle rather than trying to fix a dot on a target. Ideal on moving, or erratic targets such as a turkeys head.