Latest few episode do some really nice things, but ultimately not enough to save push the series into an “easy recommendation” category. I wouldn’t recommend it to anyone other than those already interested in the show, and whose curiosity can carry them throughout the series. The story isn’t bad, but it just doesn’t hit the right notes. The show felt great when it was just Zero and Mercenary, even with Albus tagging along. I like Holdem too, but I feel the show would have been so much better if it had a more minimal plot and focused on the interactions of those four characters as they travel and search for the Grimoire.
Something I will always remember this anime for is how Thirteen is set up as the antagonist. For every heinous deed that he is accused of, he provides logical reasoning and counter points in order to explain why they were necessary or that they weren’t actually his fault. This is good and well, but what really sells Thirteen is that his logic is just a thin veil for his true motive, giving Zero her chance at fulfilling her childish dream. While his methods and, ultimately, his actions were condemnable, Thirteen is a perfect representation of my favorite anime villain archetype. An obvious genius with little emotional capacity that commits heinous crimes in order to prop up the one thing in which they have emotional capacity for.
I’d suggest reading the source material. There’s a fan translation that just started volume 2. It’s different, but in my opinion, better. For instance, we get a more detailed explanation of sorcery and magic, which could’ve gone an entire episode. The dynamic between Mercenary and Albus is more entertaining, resulting in the latter feeling less like a third wheel. The role that the Sorcerers of Zero played in starting the war is explained better. Thirteen’s character is explained in more detail. Holdem is played more as comic relief. We also get a lot of internal monologue from Mercenary. Some sequences are also injected, such as the whole scene with the barmaid in episode 7, and the fight between Holdem and Mercenary in episode 3.
The whole exchange between Holdem and Mercenary is given a few short paragraphs in the novel. The mechanics of beast fallen going feral are also different, and introduced at a different time. Most of episodes 2 and 4 don’t happen. The flashbacks from the first 6 episodes never happen. There is, overall, less violence, better characterization, and more concrete explanation in the light novel. I get why they made these changes in the anime: it wouldn’t transfer well. However, it interferes with canon a bit more than is welcome. I often see people confused at how stuff is explained in the anime and just shake my head.