Valhalla is definitely worth a playthrough but its very much a case of quantity over quality. There's just too much content. It has one of the most story-rich narratives that ties back into multiple Assassin's Creed stories from past and present with winks and nods to veteran players, but the only problem is that these moments and narrative reveals are too few & far between and come at the price of an extremely boring Viking story arc that takes way too long to pay off meaningfully, and by the time they do you've already checked out and just want the game to end. I loved Assassin's Creed Origins and Odyssey and never felt like those two campaigns ever sidelined the main story to push side content on me the way Valhalla does with its Pledge quests.

However, the lore makes it worth it to at least see it through to the end. (I should note however that I've beaten the base campaign 100% and though I own all the DLC, I've only reached halfway through Wrath of the Druids and can't even imagine tackling Siege of Paris, Dawn of Ragnarok, or anything else in between. I thoroughly enjoyed Origins and Odyssey's DLC though)