I've had a half dozen Raptors dating back to when they were first introduced. All are still running and up till last year were all running 24/7 for many years. WD Enterprise class drives are as well built as anything out there. There are faster drives now days if you look only at sustained transfer speeds, but the Raptor prevails for access times. Perfect for servers and other multitasking applications.
I'll add that WD warranty service is quite good, but I only had to use it once many years ago.
The 2TB Caviar Black SATA-3 drives are actually faster for sustained transfers.
It's unfortunate that WD and Seagate are forced to sell super-cheap HDDs to maintain a market advantage, but neither should be judged based on performance or durability of those low-end drives. I for one am glad that WD is dedicated to continue making high-end enterprise drives.