The foil is easy to cut and fit. It has a bit of "body" so it holds its shape. It seems to work well, my radiator is on a very cold outside wall, and I am sure the room heats up quicker than before (I hope that's more than wishful thinking). The sticky pads have really strong glue. I fitted the foil in about ten minutes, and just needed a pair of scissors to cut to size. I put two full-width pieces behind the main part of the radiator and two ~4" strips behind the outer edges, to avoid the brackets.
I stuck the pads to the foil and left the protective paper on until I had fed the foil behind the radiator.
My radiator is really close to the wall and under a windowsill so it was difficult to get the top of the foil far enough below the top of the radiator so that it can't be seen from across the room. I tried to adjust afterwards, but couldn't move the sticky pad. I only have a pad at each top corner, so I've folded/pushed as much foil down as I could.
The foil is absolutely great for the job, I just needed to be more patient in working out how to get it far enough down behind the radiator, before I pressed the pads to make them stick. If you are handy or crafty, you will be great at this. If you are slapdash like me, ask your careful family member/friend to do it for you, or like me, just accept a little bit of foil showing, if you don't have the patience to make it perfect :)