It works great as it should when installed. I found it very annoying to get the right height between pickup and strings because (differently than the guitar version) this one does not have a neck radius adjustment, so it is nearly impossible to match the string to pickup height as the installation manual asks. However, if you are using a GR-55 and can adjust the gain of each strings, you can compensate the height issue then.
Other that that it works great and comes with so many mounting options which allows you to chose how to mount the controller on your bass, including a way of mounting it on the back side - which I think is great since this is not the most good looking type of gear.