This used to be very bumpy and narrow and I rated it one of the hardest stretches I've ever done. Nearly all of it has now been remade (2003/2004), partly widened and resurfaced, especially the previously awful eastern drop down into Bourg which for me makes it the number 2 in this area. The first section from Flumet is relatively easy, climbing up on wide gentle hairpins and a superb sufrface with some potential knee-down stretches, especially the section before the Lac du Rosseland and just past it to the top of the pass..
The east side if the pass starts (from the top) pretty nicely, but after a few kilometres where the road drops over the head of a glaciated valley and you can be greeted with a fantastic view of Mont Blanc if you're lucky. The bottom section used to be awful, but has been widened and flattened at the hairpins and almost totally resurfaced. It runs through thick woods and eventually levels out down to Bourg St. Maurice.