"We've recently had both our bathrooms done up and have had three of these parts cause us issues.
The first part failed during installation, after tightening it up and testing the connection it dripped slightly. Further tightening caused the metal tap connector to slice through the plastic rim holding it in place causing an even worse leak and requiring the part to be replaced.
The second and third parts failed post installation, frustratingly after all the tiling had been completed. The tap connectors both developed a very slow leak, once discovered, again the connectors were tightened and the slow leak stopped, however, again the tightening caused the same problem with the plastic rim and they both began to leak (at some rate) from the rear of the metal tap connector.
In summary, they work fine so as long as you make sure that you DO NOT over-tighten them. The fact that it is so hard to get a secure fit without over-tightening them makes them, in my eyes, a poor product and I won't be using them again."