I have been working on a map generator... I have been looking at random collections of tiles for so long I can't tell a good map from a bad one.

Screenshots on Imgur

http://imgur.com/a/iBJBJ

It's a bit...swirly. The forest one in particular jumped out as "that's not how a forest is laid out". The first height map put the effect to good use, but if I zoom out I'd expect an archipelago or a continent or something, not more of the interlaced water and land.

The biome map I like. The mountain lake is an interesting feature. The big lake in the center is a good opportunity for an island or two. Having deserts on the sides and water in the center seems geographically unlikely, but realism is overrated and I'm not a geographer, what do I know?

Desert and Tundra could probably use some little features to brighten up the place: an oasis, a stony outcropping, whatever.

Overall, looking good.