Works great! UPDATE(2016/Jan): Drive just died, click click click
I use this drive to provide Time Machine backups for the 3 Macs in the house. Two of my Macs have USB2 ports, so these ports dominate the write speeds to the disk. Even though the TM backups took 20 or 30 min each, these were the first time backups which amounted to 60-90GB.
Silent, low power, reliable (so far); The small form factor and self-powered aspects are pluses as well
None; Update(2016/Jan): I used it a few times (maybe 4) and had it unplugged sitting on my desk; I used it just now for another Time Machine backup and it started to act weird; It would unmount spontaneously.