In 6 years of tramping through briars and thickets, it has never failed or had a problem.
Thats because it's made by POLLINGTON! What do you expect?
I have a 42mm BSA red dot. I love it. I can't find a downside to it except the battery may go dead at the last moment when you need it the most. As Fieldmouse said. It eliminates your peep, because of the design of the scope. If your form is off, you can't see the dot.