This product might not be the prettiest draught excluder, but it is extremely easy to cut to size and it works an absolute treat. No need for any nails or hooks or to constantly adjust it. You cut it to size, slip it around the door and it's done.
We had a pretty big gap under the front door to our flat (leading on to corridor, not outside)which let in lots of cold air. The device has completely sealed that gap and we can already notice a huge difference to the temperature of our room.
The only reason it gets a four rather than a five is that it looks a bit odd. it's not particularly offensive, but I think you can get more discreet ones that fit under the door (but are much more complicated to install), and don't poke out either side of the door the way this one does.