I walked from Pau to Somport in early April this year. Because my friends suffered from foot injuries which meant that we were falling behind our schedule[we had prebooked return flights to Australia from Madrid] they took a bus from Bourse to Confranc. It was on a Sunday and they had to wait hours before the one bus for the day came through. I walked the 40 km. from Sarrance to Somport in a little over 10 hours, and must admit that I had my head down for a lot of the time, as I concentrated on maintaining a steady pace. Even so, the scenery was spectacular and because I travelled a fair distance that day, I had the advantage of seeing the mountains unfold as I got nearer and nearer. I had a problem just short of Somport [perhaps where the Ancienne Route d"Espane joins the Somport road ] where the arrows actually showed I was going in the wrong direction. I retraced my steps for about 500 m where I asked some skiers in a car park which way I should be going. They turned me around again and sent me back where I had already been. I did not need that!
The comment about the steep descent from Somport is accurate, and it is fairly hard going. When I was there in early Spring the path for the first km or so was covered with frozen hard-packed snow and was quite dangerous. But the scenery was lovely, and to Australian eyes used to years of drought the sheer greenness was a delight.
Buen camino