Season 11 was kind of meh, but there was a lot of very interesting new info, the most striking of which was a reasonably well documented link between Vikings and Knights Templar. There was also info reinforcing the link between the island and both of those groups.
The narration continues to annoy me but I'm probably in a very tiny group that has been following this from the beginning, so I do understand the need for a certain amount of repetition. There are a lot of threads to follow in this show so background is very much essential to the telling of the tale.
No actual treasure was unearthed this season, but it was still informative and I enjoyed it.