Pros: Good airflow with decent noise level; red LEDs can look awesome
Cons: Too noisy at full power for silence freaks, red LEDs won't look great with every build
Very happy with these fans so far... I'm using 3 of them as top/rear exhaust in my CM Storm Trooper case and have them hooked up to a Sunbeam fan controller. They move a pretty decent amount of air and do not create tons of noise. They are very noticeable at full power, but they aren't loud per-se. Haven't noticed any clicking on them in a little over a month of use, which I like.
If you care about a super-quiet case, make sure you have a fan controller for these. Other than that, I don't have any complaints really. They're nice fans and the red LEDs work great with my case and with any build that can incorporate red into the color scheme.