Just got this delivered and up on 30 Oct 2010. As long as you do not compare it with SSD, it is fine. However, amongst conventional HDDs, it is the fastest I have ever used for my basic HDD with windows 7. Over 2010, I have used conventional 7200 rpm Seagate 1 TB, and a Western Digital Caviar Black 1 TB wd 1002faex. Compared with these, 2TB caviar Black is around 15-20% faster than the 1 TB present Seagate, and more than 10% faster than 1 TB Caviar Black. Backups take lesser time (1-2 mins less for a 15-20 GB ghost/acronis/paragon image). Response and access is great. 2 TB is quite a lot but I have loaded my OS, photos, docs, music, and movies on this 2 TB. OS Image backups reside on a 1 TB Caviar Black, enabling faster backups and recovery. Other backups reside on a conventional HDD (spare internal Seagate 1 TB converted to external through an enclosure and connected to desktop PC via SATA which I find a faster solution than a pure external HDD connected with USB 2.0). Overall, this combination enables fast access, backups, and recovery.
SSDs are definitely faster but not in my priorities at this time with the price. Perhaps later in 2011 when I will put a SSD and use Caviar Black 2TB as the main HDD (for all other stuff except OS).
I have filled my mac pro with these drives, buying the first one when they were only 1 Tb versions available. Great for video (PRORES) and no failures yet (!) Now have one as my boot drive and the machine is a little nipier than before.
The drive seemed OK to start with although it wasn't as fast as I had hoped. However, 10 months later, I returned it to WD, due to mounting and writing issues and noise (and it appeared to be unrepairable with the usual software). I noticed that their returns/repair info say that a reconditioned drive may be issued in return, plus I had to pay the postage. Keep the box, packaging and electrostatic bag if you buy one because WD require drives to be properly packaged if returned. Update - WD have sent me a new drive, 2 weeks later, so their warranty service has been good and it was easy to use via their web site. The new one is running well and is very quiet after the initial start-up.
When they work, they do exactly when the spec says; fast and reliable - up to a point. Of the three I bought two failed within a week but I suspect this was more due to the near total lack of packaging supplied by eXpansys (one thin plastic Royal Mail envelope only).
That said eXpansys did take them back quickly and painlessly.
I have since replaced the faulty drive with more of the same but from a supplier who understands the need to pack these items with a little more care.