I like them I have to say, although they don't do exactly what I wanted them to do, which was allow me to stand on them with the door closed to put bikes on and off the roof...you need prehensile toes to do that as there's only about 0.5" of room with the door closed. But they do help with the doors open and they look nice. Also helpful for kids or older passengers to get in and out.
Worth the £500+ for purchase, shipping and fitting? Probably not logically but I would do it again on balance. I'll have the car for a few years so if you absorb the cost over the lifetime of ownership it ain't too bad.