I walked it last year in September. There are plenty of way markings and signage and water points. It's sunny and hot. It's not a difficult walk, but there are some long sections. It seemed almost like Downland England. Look out for left over grapes after the harvest.
I used the official VF app and it worked fine. The route direct and easy enough to walk. But there are several alternative routes that would need other considerations. Your phone will do all the GPS stuff.
The big towns are full of tourists, but the small hilltops are a delight to stay in. I'd choose a convent or monastery hostel first as you get views that are unique.
I was able to stay in all the main hostels and only a few felt busy or crowded. It helps if you call ahead to the hostel for next day, to introduce yourself and make contact. The Italians seem to find that a familiarisation.
As it's the holiday end of season some hostels close or offer a limited usage. I found myself in a fairly large hostel on my own one night. I don't know why I got it. But I was let in by an old woman, who I think was helping her hospitalero son.
In Rome the main hostel gives you 2 nights on a donation. That's a great deal.
I mostly finished each stage by early afternoon, allowing time for a meal. Then get in to the hostel at 3-4 pm. Then some rest, then back out later for a meal. And so the days pass quite pleasantly and quickly.
At St Peter's Square you can quickly get through the crowds. Just go to the check in areas and the police will let you through. You get into a small hallway and pick up your certificate at a desk.
I'm thinking of doing the next stage on down to Sicily, maybe this year.