I had one that I used for conservatory roofs and fascias, it is not a waterfed pole as in the "reach and wash" category. first of all the water flows through the middle of the pole and not through 5mm pole hose, so pressure will be lost.
Putting fairy on the brush and using tap water wont work!! it will spot all over the window.
For window cleaning the item is useless!!
For conservatory roofs, fascias and soffits its pretty good!!
But you can get one cheaper I think I paid £12.50 for mine about 18months ago.
Matt