It's a memorable spot for sure! I didn't visit when doing the Camino but have been several other times.
It's worth noting though that depending on when you would consider going, you may need to book in advance. Since it was used in scenes of Game of Thrones, it's become very popular and there were long lines to visit.
You now need a ticket with a reserved time slot to visit during high tourism times - summer, Easter etc. I believe it's still free though. You can reserve your entrance here:
https://www.tiketa.eus/gaztelugatxe/?lang=en
I'm pleased I've seen it as it is quite spectacular, but it can get very, very busy in the summer - even with the ticketing system. Just a heads up on that!