Grass: it does its job. It could be better, more detailed, but its fine. Except one place - city. Your city looks very "flat" and thats not very good. Try to make at least two differently high levels. Especially keep could and probably should be a little bit above other buildings. It would give your city nicer look.
Mountain/rock: texturing could be again a little bit better, more detailed by using smaller brushes, but again, its fine. What isn't fine at all is modelling. Modelling and texturing should always work together, there should always be some logic. When you have dirty line between two rocks, there should be some "reason" why dirt is there. And that reason should mostly be that its in line between two ridges. Try to raise your rocky "flakes" up and leave dirt between them on current height level. Don't forget to polish raised rocks a little bit with blur tool.
Roads: somehow, somewhere too wide for my liking, but what I would really point out is that they deserve much, much more details and effort. Change your brush size, use a smaller one, much smaller one.
Shores: that grass directly next to water line just looks non-realistic. Some sand, or dirt at least would be better. Try to draw a shoreline there. I personaly am sometimes also too lazy to do something like that, but at least don't use grass texture as bed of lakes/sea.
Spawn: You don't have to have many trees around, but it would be great if you at least added bushes and some rocks or something like that. Quite a lot of places seem a little bit too empty to me. Btw, do you know about ground effects? If you do and you just didn't want to place them there yet, OK. If you don't - take a look at Steff's tutorial and apply them. There is also one hint corresponding to ground effects, it seems you have grass texture under buildings. Thats not something you would want to do, use another texture, some which won't have (big) ground effect models. Otherwise you will experience grass growing through floors.
Still, you did fine job, there is room for improvement, of course, but If you want to have some inspiration, links to a few of my videos are below, so you can see what I was talking about here. Anyway, welcome to Noggit devs community, have a lot of fun and good luck with your future edits
.
A quick overview of my style of painting and modelling of roads and grass "hillies":
VIDEO Making of video with 20x speed:
VIDEO My level design tutorial series, they are czech only though, but you can still turn sounds off and just watch to get a few ideas:
https://www.youtube.com/playlist?list=PLsm-YJoAUKujJ98fpLd7zdJFxyclGlCKs 
