Summary: I just built my first rig and went with one of those Corsair closed-loop water-coolers for my CPU, which works fine but is rather loud; hence, the zalman "quiet" case fan upgrade from the default corsair fans. However, the Zalmans are just as loud as I can't use the silicon pins on the radiator.
Summary: The good: It's a fan. It moves air. It seems to be reliable. It has a long enough power lead that it will reach most parts of a midtower case. The bad: It's not a particularly quiet fan. There is a certain amount of nouse created by moving air around. You WILL hear this fan in action. When I added this as a front case fan (to an Antec Sonata III case) it was noticeably louder. I'd say it's quieter than the average fan but certainly not silent.