To be honest, Season 1 was more fun. Overlord is a comedy power fantasy with a villain protagonist. Ainz Ooal Gown is the eponymous Overlord of the Great Tomb of Nazarick and its colossally evil minions. Some of the more important ones for this season include:

1. Demiurge, a super-intelligent devil. Even Ainz doesn't understand how evil Demiurge is, e.g. the parchment from his "two-legged sheep" in ep.4. He's prepared lots of it.

2. Cocytus, a truck-sized insect with freeze-breath and a samurai code. He's loyal, not evil. He'll massacre you respectfully.

3. Entoma Vasilissa Zeta, who's an insect swarm in a sack. She's also one of Ainz's maids and you'll think she's human for about two seconds, until you've noticed the mask, the antennae and so on. She doesn't actually hate humans, though. She can be friendly. She just thinks we're food.

4. Sebas Tian, who's awesome. I worship Sebas. He's an elderly, stone-faced butler who takes no nonsense. (He's also voiced by Shigeru Chiba, which was weird for Tomoko as she associates that actor with outrageous comedy. He played Megane in Urusei Yatsura.) He even understands altruism, although he'd kill babies if Ainz ordered it. He's been sent to investigate the Re-Estize capital, so he's a major character this season.

5. Solution Epsilon, who's a little mysterious. I couldn't remember what was monstrous about her, but there's a Season 1 scene where she uses her abilities. Ewwww. She's accompanying Sebas and bitching whenever he doesn't kill.

Season 1 was a blast. It had all these anti-people and more, wreaking havoc that usually ended in good people being lucky and bad people being, uh, not. This year, though, the show's shifted genres. It's no longer just a power fantasy. Ainz isn't really the hero of his own show any more, although obviously he's still important. The narrative focus has shifted. There's lots of worldbuilding, with countries, factions, plans and religions. There are goodies, baddies and Ainz's lot in Nazarick (i.e. our baddies). The narrative's happy to use Nazarick either as anti-heroes (e.g. Sebas) or as flat-out villains (e.g. the lizardman story arc).

Interestingly, the show's graduated from relying on Disgusting Bloodthirsty Evil is Cool. There's still plenty of that, of course, but there are also unambiguously good heroes who get their own adventures, story arcs, fights and character development. The politics is complicated and still unresolved at the end. (Season 3 came out only three months after Season 2.) Princess Renner, for instance. What the hell?

The show's also developed a habit of wrong-footing you. It'll seem to be building up to a big fight... which then happens offscreen as the episode focuses on something else entirely. (This makes sense, though, since everyone in Nazarick is so powerful that almost any fight is a foregone conclusion.) I knew the season finale would twist and turn, involving as it does a battle between at least three different sides, but even I was surprised by how far it slithered away from anything I'd been expecting.

How watchable is all this? Well, it's getting harder to root for Nazarick. The lizardman arc is using them as pure 100% villains, albeit slightly less so than was threatened by its set-up at the end of Season 1. The arc ultimately has a upbeat ending, but that's still the icing on a big, bloody cake of evil. That said, though, it's still good, villainous fun and I respect the show for not trying to stay in safe spaces. Besides, Ainz is a fantastically good boss and there's a lot to like in the warm, polite, bloodily evil family of everyone in Nazarick. (Ep.13 even made me briefly empathise with Demiurge and his artificially created situation by, literally, gods.)

Frivolous observation: at one point, there's discussion of cooking abilities. Tomoko and I wondered if anyone needed food in Nazarick. Ainz is a skeleton, Shalltear is a vampire, etc. If you cooked a meal, would anyone eat it? Answer: yes. The Homunculus maids, for instance, have a species penalty of needing to eat a lot several times a day.

Tomoko wasn't keen on the female cast's characterisation. Albedo and Shalltear regard Ainz as a walking aphrodisiac. Crusch Lulu responds very readily to Zaryusu's attentions, there's Renner/Climb, etc. None of those individually are objectionable (and the women are often downright scary rather than fantasy material), but adding them all up still smells a bit of Otaku-Bait Anime. (Tomoko's still going to watch Season 3, though.)

It's quite an interesting season, I think. Season 1 is an easier recommendation, mind you. It's more fun. However here the show's spreads its wings and becoming more complex and challenging. I like how it writes the lizardmen, for instance. It's pulling double and treble bluffs on the audience, as you try to fathom which level of evil or good is really on top in Ainz's plans. I'm still first in line for Season 3.