Summary: Even with the provided low noise adapter, these fans are very noisy. I have 3 of them in my system (2 intake, 1 exhaust), and all three are very loud. One of them is also making another type of noise all together, maybe a coil whine.
Pros: This is a good fan. I'm using one as an exhaust in a Corsair Air 540 case. It does the job of the stock fan, and it looks better with the red LED. The LED is fairly bright. I've used Cooler Master red LED fans before, and the Corsair versions are much brighter with seemingly the same performance....
Cons: The holes where you screw in the fan are not very good. It feels like the screws will not fit inside like you are stripping them, but the screws will screw in. It's not really a big deal in the end, but it is worth noting.
Summary: Overall it is great case fan, just a little pricey. I spent the extra money because I wanted all of the fans on my case to be the same, but if you don't care about brands there are definitely cheaper options.
Summary: the build quality seems overall impressive but noise level makes "quiet" a mis-advertising to say the least
Pros: -Moves LOTS of air -Looks good doing it -It's purple
Cons: -noise i will take off 2 eggs instead of 1 because this fan is specifically advertised as "quiet edition". even after turning my fan controller to minimal of the 3 modes, the fan is still the loudest in my tower and loud enough to bug me when i'm trying to sleep