Their prices are very cheap, so I looked into them.
I've shot 2 different Glocks, one rental and one personal, and both had malfunctions within two magazines. The rental one was particularly bad, and I had to turn it in with less than 1/2 a box of white box 9mm ball ammo shot through it. (...it's not limp-wristing, I use a USP Compact on a regular basis, a gun well known for limp-wrist malfunctions) I know it's a rental, but still...They sell their rentals and rotate them out with new on a regular basis.
The buttons are too small, the grip is too thick, and grip angle is awkward, it looks and feels cheap.... I'm hear rumblings online and in the shop about the Gen 4's feeding problems, ejecting problems...
I'm glad you guys like 'em though, I tried!