Mistland is supposed to be hard / foggy / difficult terrain / etc...
You just came from Plains which is basically a flat boring open space, now you get the quite opposite.
I hate the svamp, more than any biome, it's dark and wet and loads of water and annoying leeches and hard hitting mobs.... but.... it's something to play/grind through.

when the next biome comes, mistlands will be for you how svamp is now for me.
I like the diversity, that we have many biomes, some people love/hate different biomes.
=)