Please note I talk from my own taste in mapping.
Some parts looks really nice, but overall to much inconsistency. With that I mean that the area/house/tunnel or what not is originally built by someone "in the game", it has a history that follows the world and so on, it's not just about making it look nice, but make it look like it belongs!
1.st picture, the floor looks really strange and has no real 'purpose' why would anyone (as a npc/part of the lore) build like that? It mainly looks like the mapper wanted to do something different, but different is not always better.
2.nd picture, really lovely area but why would anyone put up fences that has no use? Or several wells in a room without a door, it seems it has something to o with butchering, but how are the butcher supposedly gonna use that area?
4.th pic, really nice, the floor and details would make it a nice area to explore/go through!
5.th pic, well I like this type of mapping, with multiple levels and such, but it's a bit messy and fire and lava, mixed with living trees and such makes it look a bit weird. I would remove the living trees , make the big stones stop burning and adjust some of the frames. Then it would be more consistent.
6.th pic looks cool, but again burning stones. Also in a game perspective it's not good to build multiple stairs you can climb in a row if the game is suppose to have pvp in it. As you can never kill/trap or attack a player jumping 3 stairs up and down. I agree it looks nice but simply doesn't suit the game mechanics.
Rook pics: _/