A great hike with fantastic views, getting progressively more difficult.
The first part of the route is easy: a wide, flat trail, gently going upwards. It follows the cliffside and thus offers a great view over the valley. It also offers a great initial conditioning for looking down extremely steep slopes. The technically and physically easy part ends when you reach the nearly invisible path that leads up to the avalanche barriers.
The trail to the barriers is on a 45+ degree slope and it zig-zags a lot - it is also slightly inclined and requires a sure foot, but is otherwise not too difficult. If you are afraid of heights you will understand it when you have arrived at this point.
Later on, the trail arrives at a large rocky crevice that is extremely steep and that requires some experience, although it is not particularly dangerous in dry weather (but I wouldn't try it after a rain). Many crows flied overhead, surprised by my ascent. After considerable effort I arrived at a slightly easier path onto grass, just under the avalanche barriers.
Going through the avalanche barriers was fun! The path was steep and went at some places around the barriers, while at others there little doors through which it passed to the other side. At some point you exit the barrier region.. and the view is magnificent:
A bit more walking and you find yourself at the start of the last part of the route... with a view down to the lac inferieur de Fully.The trail is not so steep here, but at some point it enters rocky terrain and the lack of oxygen starts to become noticeable. However, you do get some great views.
And finally... the peak - the final part is quite difficult and it is very easy to go off trail by mistake (as I did the first time). Unstable and amazingly sharp rocks make going down extremely difficult. The first time I tried it, I personally had a hard time as I lost the trail amidst the confusing rocks and stopped just 50 meters shy of the cross itself, findind no plausible way of reaching the top. Going back down while being off-trail was difficult due to the loose rocks and wet under-soil.
The second time we tried this, 5 years later, we made the same mistake near the peak. However, this time the weather was perfect and we just backtracked until we came across the right part of the path. Under those conditions, there is no real difficulty about this hike, although the path is pretty steep and an experienced foot is needed.