Well built and quite nice looking. - Aero Precision M4E1 AR-15 16in 5.56 Mid Barrel Complete Upper Receiver with Flash Hider

Quick run down, as I haven't gotten to actually get out to a range yet to evaluate performance:

Pros -

1. This thing's robust. Great finish on the cerakote and everything is tightened down properly, as you'd expect from Aero.

2. Barrel doesn't have any sort of burrs or other issues, nitriding is smooth and shiny. Gas block looks to be in good order.

3. Enhanced upper locks into the normal M4E1 lower snugly. No real complaints about wobble there. But not so snug in my other, non-Aero lower.

4. Nice and light. As a full build, and before adding on lights or a full mag, I'm sitting at 6.8 LBS. Not too bad.

Cons -

1. If you're expecting the color to match Magpul? It does not. Magpul's is more greenish in hue, Aero's is more brown. If that's not a concern and you're into the 50 Shades of FDE thing? Go for it.

These things are great if you can find them in stock. Just remember you're not getting a BCG or charging handle though.