Based on my experience with the first generation WD 36.7GB Raptors, I disagree entirely.
I build a brand new system a couple years back, and I put 2x36.7GB Raptors in a RAID-0 array, hoping for a blazing fast system. It was margainally faster (measurable by benchmark, not by human observation) then the same configuration with higher end 7200rpm drives.
Next, I tried a single 36.7GB as a boot, the speed and day to day performance was identical to the RAID-0 configuration.
Third, I put the 36.7GB for the page file and temporary files, this was the fastest configuration yet, but only when actually paging. For the price of the two Raptor drives I could have purchased enough RAM to make up the difference in speed, plus a larger then 2x36.7GB single drive which ran quieter.
Skip ahead to when I installed Vista, Vista is substantially faster (to the human, as well as to timed bootups and other operations) on a 400GB Seagate 7200.10 NCQ+TCQ enabled drive then on the RAID-0 pair of Raptors.
The current generation of Raptors supports NCQ, which might make the difference, but I'm not sure I'd invest in them again just to find out.
Lastly, one of my Raptors has just recently started reporting SMART errors. Enough that I don't trust it with anything important, but not enough to get WD to warranty the drive.
As far as noise, they are slightly noisier then the 7200rpm drives, but not substantially. Heat is a major factor though, if you don't have adiquate heating in your case -- Even to touch the Raptors are a lot warmer then any other drive in my system. I've currently got an Antec P180 case, which isolates the drives from the rest of my system and gives them private ventalation, even so, the power supply and two Raptor drives together put out more heat then the entire rest of my system, including two Seagate 400GB 7200.10 drives, and dual/SLI'd video cards.