The controller works, but if I turn the fans down to anything less than about 90% speed the fans make an awful high pitched whining noise. The construction of the product seems solid, however I would not recommend this product for controlling 3 pin fans. I have not tested with 4 pin or 2 pin fans so I can't comment on those. I believe the controller is running a duty cycle on the voltage output instead of just reducing the voltage via resistance, thus leading to the noise.
This fan speed controller works well. It has a connection that will work with 2, 3, and 4 pin fans. Would buy another one or two, but they seem to be out of stock often.