Here's some friendly critiques for worldpainter terrain, if you don't mind.

Good mountain shape: though it is a bit too steep on the slopes and flat on the top. For good looking mountains you'd want a more of a 45 degree slope on average, and you'd typically want them a bit more pointy, although that second point depends on the type of geology you trying go for. Also, if you want to easily create mountains with more interesting gulleys and chutes on the side try looking online for some custom brushes.
About terrain: you've done ok, better than many other people I've seen. The problem is that it looks kind of layered. My tip for less layered terrain to try painting it mainly by gradient/steepness and elevation supplementing it for things like sand and snow. Speaking of snow, it is critically important that you transition the terrain for no snow to snow as smooth as possible, because snow is especially noticeable. I usually do that by assigning a certain elevation to a gradient below which snow will be and them going up as I go up in elevation. Same applies to the frost layer, when you don't have the entire map covered in frost.
For all these gradient things I usually paint them at full intensity, except sand. For sand I just assign a gradient below which sand will be present (usually 15%), and paint it by eye, trying to stay close to the shoreline. For gradients I usually do 15% increments, with terrain of bare grass (as base), permadirt (30%), gravel (45%), and stone (60%).
About ecology: You did a good job in that, dare I say. There's just 2 minor things: usually you wouldn't want tall grass under the frost layer, so try putting bare grass instead of grass, Also, is it just me or are the trees kinda big for this terrain, maybe.
Overall you did a pretty good job with your product, so good job and keep up the good work!

P.S. I wrote this critique because first: I was in the exact same shoes as you are about a year ago, and also I just felt like helping some people out today, partially to better my own spirits.

Sorry for this huge comment, if you read all this you are a legend.

:)
 -Emil

Spectacular. Keep going.