Trevor.
Just to elaborate on what Kate has said the actual walk is about 2.5 miles from the bottom of the canyon to the top with about 1500ft of ascent.
Starts off level by the river and then climbs steeply up some zig zags to a path that runs between the Angels Landing rock and the canyon wall.
Then comes Kates Walters Wiggles. These are a series of VERY steep zig zags carved out of the rock which lead up to Scout Outlook which is pretty much where I took the photo . (apparently the path was built by an organisation called the CCC. This was the Civilian Conservation Corps and was set up by the US government in the depression in the 30s to get young people working. Seems they did quite a bit of work in various US National Parks building paths etc. Certainly without this path this would be a serious rock climb, not a walk and a scramble)
Some people stop here, the views are great and if you are atall not good with heights the going gets very exposed from here. I have done Crib Cogh and Striding Edge a few times but I reckon they are a picnic compared to this. As Kate says it is scary even with the chains, but not to be missed.
Zig zags from the canyon bottom
Walters Wiggles