As an under sink filter goes, the AQ5200 is the best. The system is easy to install and cartridges are quick and easy to change. The filters last a long time. I'm on a well and this filter makes the water taste and smell perfect. These cartridges were an automatic upgrade from a previous version and really do the job.
Then new design seems to have been intended to improve replacement difficulty but, although better, is still not easy. Since the mounting is 2 screws slotted through a plastic backing, it will always be loose and pop off when you attempt to replace the cartridge cases into the base. also recently one of the O rings went bad and when water was turned on it sprayed out all along the seam - quite the mess.