I rather like
these fans, but there are a few exceptions.
I used them because I needed 25mm thick fans for my Antec SLK3700AMB cases. These didn't quite work with the plastic clips in the cases, which I was intending to remove anyway, because they rattle too much.
These fans also don't have standard holes on both sides - you can't have grilles on both sides of the fan, unless you use some kind of machine screw - I use 6/32 machine screws with matching nuts.
The end result, however, is a fan with acceptable noise levels and very good airflow. The only noise I can hear from it is the rushing of air - no motor noise. Put it with a fanbus, and you can tune the noise to almost nothing if you want to - and if your case temps can stand the reduction in convection.
At any rate, I definitely like these fans. I've also used some of Evercool's regular plastic fans, and they've been good to me too.