Wow, what a delightful surprise! I'm a huge NetHack fan and have been waiting a long time for the official 3.7 release before switching over to it. I've been a 3.6 holdout, haha.

AFAIK, the backend has moved a lot of map generation logic (and exposure of other data) to a Lua API, which is quite exciting as something for people to play with in tooling, forks, mods, etc.

Minor spoilers below:

I heard about some great balance adjustments that help to mitigate over-reliance on a single kit, such as making certain extrinsic resistances (e.g. wearing rings) stronger than their intrinsic counterparts, which adds to the decision-making in choosing what to equip. Another change I'm really excited for is the unicorn horn no longer being usable for "restore ability", so ability-draining effects (of which there are many) are a more significant threat (they were effectively zero threat until now).

Also very cool to hear the quest is now possible to do early (despite being a Bad Idea) as that has great implications for speedrunning or "fewest turns" runs.

Can't wait to dive in!