Asetek Waterchill Hard Drive Water Cooler does indeed do what it was meant to do. It provided great cooling to hot hard drives like the Western Digital Raptor. Installation is extremely easy and only requires 4 screws. The provided thermal interface material is really easy to use and work with. The Hard Drive Water Cooler is an excellent cooling unit for water-cooling enthusiasts.
There is one drawback that I can see. The Hard Drive Water Cooler takes up one additional 3.5" drive bay, which might bother some people who run RAID arrays. The main concern would be the installation in cases such as the Antec Super Lanboy, where the hard drive cage is placed perpendicular to the 5.25" drive bays. For the traditional cases that have the hard drive cage lined up in parallel with the 5.25" drive bay, there would be no problems. But with the hard drive cage facing the side case panel, routing of tubes would prove to be virtually impossible, unless you find some small 90º elbows.
Overall, this Hard Drive Water Cooler is a great product, but coming in at a price of around $50, it's not something everyone can jump on. The price is indeed a little steep considering this unit is not extremely necessary. A regular system intake fan will be enough for keeping the hard drive cool. For enthusiasts who want to have the best of the best and have their systems running nice and cool, then this would be a great addition.