I had it on my XR2 back in the early 1990s. There was a slight rainbow effect in certain lights, but it wasn't intrusive at all.
And even in Sussex, it was extremely handy indeed. I'm not as far north as neilgcal, but we still get minus 10 and the frost can stay for days in some places.
I've ordered the winter pack, obviously, so we'll see how the heated washer jets do.
Rolfe.