I used this poncho when I completed the Yorkshire 3 Peaks challenge in March 2012.
It certainly kept the worst of the weather off and also protected my backpack, so the contents of that were kept dry as well.
It is very light and for general walking worked well.
On the top of the peaks where it was very windy the poncho did flap around a bit which is to be expected. The popper that is supposed to keep the bottom seams connected and reduce this kept coming undone so it was not as useful as it could have been. Some sort of proper strap may be more useful.
Overall it worked as expected.