Functional, but far from ideal. - Amend2 AR-15 10 Round Magazine Mod-2 Model

Relative to their most direct competitor, Magpul, these magazines fall short in a number of ways
I purchased three of these, and all three needed finishing before they were usable. All of them had plastic molding remnants in the bolt lug channel and around the projectile end of the feed lips.
Although it hasn't caused function issue, the follower in one of my magazines is slightly malformed, with bubbling in the plastic all around the rim of the front end. I feel it's indicative of, like the previous issue, poor quality control.
Relative to the likes of Magpul, Lancer, Hexmag, and even UTG, the walls of these magazines have much more flex. Fully loaded, they have more flex than any of the above empty. When dropped, from chest height, it's not at all uncommon for one or two rounds to pop out.
Spring tension appears to be slightly less than that of Lancer or Magpul, and as such is easier to shake rounds free/out of place with harsh movement.

With all this said, however, they have performed well. They have not caused any failures in ~600 rounds, I just don't know that I can trust them under more adverse conditions or harsh use given the issues that are present.