I know many people here are refraining from commenting on the subject due to issues of association, but I'm free to speak my mind on the matter since I have no such associations.

For most people that don't shoot much, they're probably perfectly fine...  The occasional malfunction just reinforces the "AR-15's are malfunctioning junk" mentality so many have heard over the years.  They will probably shoot a few hundred rounds in their AR throughout their lifetimes, and be happy with it...

I've just seen too many problems with them to justify spending the money on a barrel that requires work right from the start just to get it working reliably.  Personally, I've NEVER seen a single Sota Arms upper / barrel that functioned 100% reliably from the start.  Granted that perspective is quite skewed since people often bring malfunctioning firearms to people that know how to fix them - so the 'fixers' often only see the problematic ones.  However, all the ones I've seen have all needed some level of 'work' to get them shooting & cycling reliably with good accuracy.

There are just far too frequent issues with chambers not quite head-spacing right, needing a little bit of careful reaming to bring them into spec to get them functioning properly.  They work just fine if you take the time to check its head-spacing, give the entire gas system a good full inspection (including checking the gas port diameter to make sure it's drilled properly for the barrel diameter & gas system length), as well as checking over the bolt carrier, gas key, staking, and gas rings.  Give the bore a good close optical inspection for burrs in the rifling and gas port hole area, and if all checks out okay, it's going to run just fine!

Sometimes you might want to check to make sure the lower tags of the upper receiver were drilled with the correct spacing for your take-down and pivot pins in your lower, but otherwise they should run fine.  I've never seen one that was so far beyond repair it wouldn't work.

My cousins, God bless their frugal endeavors, have purchased Red-X and Sota Arms uppers for their low-budget AR builds.  Two of them bought Red-X uppers (thankfully the older production ones that actually functioned pretty good - unlike the latest stuff they've been producing).  The Sota Arms upper fit the lower, quite a tight fit with pin hole spacing, but it fit.  The problem with that particular upper is that it's key-holing American Eagle 55-grain rounds at 25 yards!  He's getting minute-of-grapefruit key-holed groups at 25 yards.  If he shoots Wolf, he might as well be shooting 000 Buckshot from a sawed off short barrel shotgun.

Upon closer inspection, there's a substantial burr inside the barrel where the gas port was drilled.  There are smaller marks or imperfections in the rifling cuts as well, but that's pretty easy to take care of since it is very minimal.  Most likely the problem is that substantial burr is likely stripping some of the copper jacket off his bullets, and causing stabilization issues.

I'm waiting on some finish bore lapping supplies from an online supplier so I can fix the problem for him, but until I can get it fixed for him next month he just has to deal with an inaccurate key-holing rifle.  I'm sure once the burr is removed it will likely shoot just fine.  His chamber appeared to be head-spaced fine though.  His bolt carrier needed a bit more staking on the gas key, but I'm not sure he bought that with the upper, or if that was from another company - I didn't look it over for any stampings or identifying marks.

Granted, a 'sampling' of under a dozen uppers is a fairly low statistical sampling, but they've all had issues that require more than a casual knowledge of the AR-15 to fix them.  The sampling that I've seen was 'biased' in that I'm typically the kind of guy people go to in order to fix their PROBLEMATIC guns.  That makes the sampling somewhat biased.

Though I've also worked on a similar number of Hesse Arms AR's, and in honest comparison, I've seen three Hesse Arms rifles (with Hesse Arms uppers) functioning reliably from the factory.  I still haven't had a person bring me a rifle that had a Sota Arms upper that functioned flawlessly.  The Hesse guns just needed stocks / triggers switched out with Magpul / VLTOR stuff...   And YES, that owner who wanted an VLTOR stock does realize his VLTOR stock costs over 50% of what he paid for his rifle...

I know the Sota Arms owner is an incredibly nice guy, and runs his business in a very service-oriented manner.  All are great things, and I look forward to seeing what products he puts out in the future...  I'm sure he has put out some very good quality products...  I just haven't seen them yet since people don't often bring me guns that don't have problems unless they want me to help show them how to swap out some parts.