Pros: These are some of the most top of the line units, Synology is the only other Mfg that is comparable. I have owned the 659 Pro II Turbo NAS w/ the Intel CPU and 3 GB memory, I am now needing another smaller unit to use as a backup device for the 659, So I am looking at the 269L with 2x 4TB drives installed.
Cons: Better have a stiff Credit Limit on your Credit Card
Cons: None, except that the power cord seems a bit precarious. One tug on the removable power cord could cause instant calamity in our office. Our tech guy got some packing tape and taped it to the unit to make it more secure.
Pros: Beautiful web interface. Supper easy setup. Quiet. Low power consumption. Easy point and click install of apps, using Qpkg.
Cons: None really, price is high, but this is just about the most full featured NAS available. DYI solutions for a low cost medial server might be a better alternative for advanced . After a couple of years I had filled my unit up, and built a 15 bay Unraid server of less than the cost of the Qnap 2 bay.