Ive ridden this route from Italy into France. Its good but the surface is very iffy in places though they were working on the Italian side in 2006 when we rode it.
Leaving Guillestre on the D902 takes you through a narrow gorge, the road sometimes on a bridge to get it through the valley. Some dangerous tunnels on corners where the trucks and buses have the right of way due to their size! It then opens up for the run to Chateau Queyras, a wriggle through the village and then out on the D947 to then make the right turn up the D205T and the Col d'Agnel.
This part is more exciting with many hairpins and mad cyclists to navigate! When I went in August 2004 the mist came in quickly from the Italian side of the Col and visibility was down to less than 5 metres, and then it was gone as quickly as it formed.
At the top there is an orientation table.