They are hideous looking and flipping huge and I wouldn't want one in a kitchen. In a kitchen, garage, loft etc. they are great, easy to fit and a piece of cake to work on. A full strip and service takes around 10 minutes. A downside for some people is the lack of their own breakdown engineers, they use the installers for breakdown work and pay for it. I like this as it means I've got no large company trying to rob my service work.
Their training courses are very informative and free. Well worth the time and effort to attend.
Parts are available through parts center or direct at a reasonable cost.