If you really want to see the col de la Machine (I hate heights so don´t ever want to do that one again) then this is a great way to get to it. Lots of corners, the surface can be a bit rough in places due to winter snow etc but a great road. Bit spooky going past the ski resorts in summer, like ghost villages. At the southern end there´s the memorial and visitor centre for the French Resistance. Link this with the Col de Rousset towards Die and it´s an amazing ride.