The terrain is fine as it is. The majority if the biomes are pretty flat and are like plains biomes. Only a few places have stairs and slabs and honestly I like as much diversity in pvp as possible so these environments are good. I would actually want more challenging biomes that possibly have lava and hilly terrain just to shake things up a bit but that's just me :P Mobs are pretty easy with the exception of witches and the border moves so slow I was able to craft a pickaxe and escape it while I was almost a block outside of it without taking damage.