I walked from Lourdes to SJPP (and then the Frances) in late September.
Loved it. Hilly terrain, but the real challenge are the distances needed in the usual stages -I was walking 8-10 hours daily. On the other side, I am slow...
Some days with a light drizzle, but paths were passable.
Signage is sometimes confusing, because there are many options. There is not a "canonical" Camino, as in the Frances.
Quite lonely, too. I met other pilgrims (just a fist, apart from Oloron) only in albergues.
The only really tough stage was between Mauleon and Saint Juste Ybarre -there is a "col", the mountain pass of Napale.
It is not a mountain, remote route, actually. The path goes from village to village, and in the forest sections (many!) you can usually always see a farm or two, in the distance. Lots of sheeps...
Local people are friendly and helpful. They start to become used to pilgrims.
Great if you are looking for a quiet walk, with beautiful landscapes. Some walking experience recommended, but not essential.