Excellent and well made product. True, you look at the price, and initially you feel you could build a NAS yourself - but this is fast, the software is a delight and I am very pleased. Have added more disks, used the cache (2x needed for RAID requirement for R/W cache), and installed a cheap 10G card. The main advantage of the 1621+ over the 1522 is the availability of the slot, and ability to upgrade the networking to 2x10G inexpensively. Very pleased.