I like them a lot. Its $400 less than most other ARs and has superb quality. Only thing missing (that matters imo) is the dust cover.
I bought one a month or two ago. Took it straight to the range. My first time using the magpul flip up iron sights, went 10/10 on ketchup packets at 35 yards with xm855 after sighting in on paper.
Still waiting for the glass/rings to come in the mail for it, went with a variable 1-4x red dot from mueller. Taking it to a nearby park for a 100yard test asap!
As the previous poster stated, it is not a piston. I have only shot penetrators (62gr) through mine, what (bulk) ammo have you others found that yours likes?