Summary: Other than the high cost, I have no complaints about this fan. The color scheme isn't great, but these are stuffed in a 4U case that never gets opened. Moves air well and doesn't have any obnoxious rattling or other sub-noises that really irritate me.
Pros: Well constructed Well packaged Quiet Moves a lot of air
Summary: I bought this to include in a case that was not supposed to have a fan. It did, but I used this one anyway. It seems to move a good amount of air, and adjusts speed based on internal temperature. well worth the purchase price. Even at full speed I don't hear this, it is extremely quiet.
Pros: I'm using this fan on an icydock mb975sp hotswap bay. The fan keeps the 3 drives spinning inside at around 33-35 degrees even under full load and does it all while be nearly silent with the low noise adapter!
Summary: I use this under my work desk to keep my laptop cool. I have to say this is the quietest computer fan I have ever owned. I liked it so much, I just bought an 80mm for an HTPC project that I am building. I recommend this fan to anyone who needs great air flow from a super quiet fan.
Summary: They are Noctua; those who know - know. Moves air quieter than any other 80 mm fan I have tried. I use nothing but Noctua fans in all my systems where they make a compatible-sized product. I may be a bit partial to Noctua but only because they continue to live up to their reputation. They generally cost a tad bit more but you definitely get what you pay.
Summary: I built a gaming system in an HTPC case thinking that I would eventually need water cooling due to cramped case conditions. Four of these fans barely make any noise and I haven't had any overheating issues yet. Wouldn't be surprised if I could get some overclocking going even with the stock heat sink. These are worth the price especially from a durability and low noise standpoint.