Very well engineered; except for a few minor fit and finish issues.  Took way longer than the 6 hours listed in the directions; took me at least 20 hours total working mainly by myself.  The BILT app is very helpful in addition to the printed directions.  One minor problem:  nut AAB (should be 1/4-20) definitely does not fit on bolt ACH in the door latch assemblies; called and ordered replacement parts and they still didn't fit; had to buy new nuts at the hardware store myself.