I made a new world that focuses on the caves, because I wanted to explore them, mainly for the new fossils. So I made my whole base in the caves with farms, pighouses, even with the moondial.
After some time I realised, that pigs in the caves don't behave as they should. Their houses (and the whole base) are built under a sinkhole light, so thet they have natural light.
They never follow me after giving them meat, they just stay there where they were. They also not allways help me fighting other creatures (but they usually do). Sometimes some of them do not leave his house at all, staying inside during the "day" phase too. They follow the light sources like torch or thermal stones, despite the fact that they shouldn't, as they come out only during the "day" phase. And when a pigman is a follower (even if he doesn't actually follow the player) and dusk falls, he doesn't go into his house (that's ok), but neither gets paniced. It won't run around like it would in the upper world, just walk normally, and of course, following the light or fire (if there is any).
Another rare bug is, that sometimes the silk disappears from the ground around a spider den. That means I could walk with normal speed around the den, but spiders were alarmed when I got near to it. This got fixed the next time I got back to the caves or reloaded the world, but it happened more times already. I only experienced it in the caves.
These are maybe not the most important bugs, as I think not too many build a whole base underground, but it would be nice if these could be patched.
World settings were: Start: Plus, Long Autumn and short winter, spring, summer, the caves are "huge", with less rain and monkeys, more treeguards, cave bananas, failed surviors and touch stones and slower disease. The world was generated a few days before the "Arts and Crafts" update. (This world is actually the one where the Labyrinth and the Moon Stone are missing, as I wrote it in an other bug report.)