I had one when we lived in the UK in a very hard water area. I absolutely hated it! Very heavy, due to the filter, and, although it said you could heat it before all the water had filtered through, this didn't work. What happened was, the water in the bottom boiled, the kettle switched off and if you unwittingly poured water into your mug, the cold water from the top reservoir slopped out all over the place (and obviously you didn't actually get any boiling water on your teabag!). Horrid and a complete waste of money.
I had one for about 3 years, it was good. Only thing was we almost never used the water filter bit (sort of defeats the object, but we live in a very, very soft water area - one advantage of the north lol). One tiny downside was it didn't hold as much water as a standard kettle due to the space needed for filter. Replaced though now as it wore out.
Had mine a couple of years now. Live in London as well.. Old kettle, I had to descale all the time. Hated it.. I've descaled the brita one 3 or 4 times but this has been because I have been neglectful of putting another filter in.