That's the North Ridge of Crib Goch, it goes at Grade 1 and is no more difficult than any of the other scrambles along there. It'll take you into Cwm Glas, which has paths down to Ynys Ettws. Or you could back traverse along the bottom of Crib Goch to Pen-y-Pass; no idea if there are any paths that way though, I've only done it in winter.

Yup, I've done that route down a couple of times on (eventually failed) attempts on the Welsh 3000s. Not the easiest track to keep to after the top section, especially in bad weather. No probs otherwise

This is the normal way down when doing the Welsh 3,000, quite easy in good weather/visibility but, could be a problem when the weather/visibility s bad !
The new Stone Monkey DVD by Alun Hughes shows Colin Donelly on his record braking run of the peaks, think his time was 4.20 or something silly like that.
Anyhow it shows the descent of Crib Goch on it, incredible the way he blasts down it !