So Far I have purchased 3 complete uppers with no complaints. I ordered an unbranded Lower parts kit again with no problems. I have no idea where all these complaints came from but one can't help but wonder how skilled the builders were to start with.
Tip for consumers: For me they made building affordable.
Products used: 3 complete AR-15 uppers, one BCG, a few ar-15 sights, one lower parts kit, and some magazines.