Ive owned a number of NEA AR's... some of the older Gen and 2 of the newer gen. The older ones weren't nearly as refined... they felt cheap IMO. But I didnt ever have a problem with them. At all... I put about 1000 rounds through each.
The new ones feel, IMO, to be of much better build quality. I, personally, really like the squared off edges and sharp lines. I think it looks really nice. The 2 newer ones I have owned had less rounds through them, but both worked fine with no issues at all.
Ive build a handful of AR's using NEA uppers, lowers or both. In my experience, their uppers and lowers worth together well, but they wont always fit correctly with other brand uppers and lowers.
With all of this said, I currently own a Norc 10.5 inch AR... of all the ARs I've owned (including DD's, spikes and other high end guns), this ones works just as well, and cost up to 1/4 the price. I got mine lightly used for $550... put a few hundred into upgraded furniture and a few bits and pieces... for less than the price of an NEA I have a gun thats customized to me, works PERFECT, never lets me down and, because its a norc, proves I'm not trying to impress anyone with fancy gear... my sub par shooting does all the talking for me. Lol.
Id buy an NEA on a great sale deal if I was in the market for one. But if you just want a really good working AR thats cheap and wont fail, try a norc. Im sure many will laugh at me... but mines great.