The trail to the top of Clouds Rest narrows above the tree line. In some places, the trail is not more than two feet wide, with a 4,000 foot drop to the right and a 1,000+ drop to the left of the trail.
From the summit of Clouds Rest, you look down on much of the center of the park. The top of Half Dome is over a thousand vertical feet below you; the valley floor is over six thousand vertical feet below.
The descent from Clouds Rest via the southern face is much steeper than the northern approach (how I ascended), but does not subject you to nearly as much exposure; I found the ascent to be much scarier.