I purchased this unit on Sept.27/13 after doing a lot of research on the internet on Thunderbolt drives. The ability to replace these drives easily without tools etc (must be replaced with Western Digital Green drives) was a strong selling point.
Knowing that this unit comes with a 3 Year Warranty is comforting because of how costly the drives are to begin with.
Operationally this unit is very quite (the competition uses a fan and every review I had read that was a big complaint).
You can register this over the internet easily through the available software, but I chose to call Western Digital and the customer support was excellent.
I would highly recommend this product and Thunderbolt over USB 2.0 or USB 3.0! The speed and connectivity is unparallelled.