This is a hard route to star. It could be great, and the start (Pablo Diablo) is excellent. The holds on the extension are sandy and there are many brittle flakes on the periphery, but the actually movement is very good and exciting. Once you reach the anchors of Pablo Diablo, veer left by throwing to the beginning of the rail system (big move, but intermediates abound). The rail itself is not very hard, just slopey and pumping, with a somewhat powerful move in the middle of the roof.
My biggest problem with the extension is the anchor placement; it is up and left of the gigantic hueco. This makes the route pretty impossible to clean and the rope rubs harshly against a lot of edges. When I did it, I climbed to the anchors and then down-climbed to back clean. It's pretty easy to do this and there really isn't a better way - I don't think the anchors could be moved to anyplace better.
The extension of Pablo Diablo. Out the roof, following the right angling, rounded flake.