To my knowledge, it's the first semi-auto shotgun that has been accepted by the US Military. If the USMC thinks it's reliable enough to use in the Sandbox, then it's good enough for me.
One of the guys at my LGS seconds that- his unit had them assigned to them, and he was completely impressed with them. I would choose one any day over a Mossy or Remington- but for now, I love my 590A1
...we should really sticky a 500 vs 870 thread... Just sayin'.