Theros is a very niche product, even moreso than Ravnica. Ravnica is very egalitarian and eclectic - you can easily incorporate any race, class, monster, etc. in Ravnica and it will feel right at home. Theros has a very specific flavor - its Greek as all hell. That's going to make it harder to incorporate species that don't show up in either Greek mythos or Theros block - Loxodons, Elves, Orcs, etc. Theros does add a nice buffer between D&D mythology and real-world mythology. Including myths like Heracles and Apollo would suck me right out of the game but Thassa and Heliod are just different enough that I can roll with it.

The Gods are neat and described well. I think getting a group that collectively all worship one deity might be difficult, and mixed groups allow for more conflicts and plot hooks. The being said, I can't see this being effective with really large groups, as you will reach a point where one player can't progress in their piety/quest without another player being obligated to interfere or take a hit themselves. Then again, you really shouldn't be playing D&D with a massive group if you value your time and sanity.

Leonin are a slightly more interesting Tabaxi, tritons are a nice twist on merfolk. The Satyrs, though, seem really powerful as player character races go. They aren't Yuan-ti pureblood bonkers, but they should be enough to give a boner to min-maxers.

Theros suffers by having most of its Greek-inspired monsters already in the MM. I'd love to see more hydra variants and sample chimeras in MOT. We get a lot of archons which is...weird. Anvilwroughts and catdog snake are both fun, though.

I think playing with party death - going to underworld while alive, going there while dead, escaping, having an Returned player or NPC along, etc. - allow for some really cool twists on the traditional story structure and anxiety beats of D&D. ( )