I have one, just waiting on my form 1 to make it a G3K SBR... Mine has 12" barrel and will have a fixed stock. I like mine a lot, and the $5 mags is a huge plus! I just ordered some mil-surp ammo for mine and will try to reload the brass, if I can find it, because it does sling brass quite a ways!
The factory trigger is not great, mine broke at 12lbs with aot of take up, but what do you expect from a battle rifle. My trigger now has a 4.5lb pull and very little take up. I also replaced the standard recoil buffer with a heavy buffer and it made a noticeable difference in recoil.
As for accuracy, 1moa out to 400 yards is attainable from the longer barreled versions using federal gold medal match ammo. Mine is not a long range rifle, more of a CQB type than anything.
It eats anything I feed it including cheap cheap Chinese steel cased ammo. I think they are a great fun for the money.
"Laws that forbid the carrying of arms disarm only those who are neither inclined nor determined to commit crimes. Such laws make things worse for the assaulted and better for the assailants." - Thomas Jefferson, 1776