Dan - nice picture, and yes Fairy Glen (Ffos Noddyn in Welsh) is hard to photograph - that little segment of sky at the top is overexposed on most of my pictures. It's also a slippery, tricky place to get just the viewpoint you want. Worth revisiting when water levels are higher and lower. I like the way you can see right up the gorge (water must have been low-ish?) . You've selected an interesting shutter time, enough to show movement in the water but short enough not to 'streak' the foam; a slightly longer time would give a stronger feeling of flow.