I think you've done a very good job with the visuals on "Walking Home". The only thing that sticks out to me is the pole near the water (see 1st attached screenshot). I'd do something like place a brick at the end so it doesn't abruptly cut off (see 2nd screenshot) - though at least it's lined up with the edge nicely. Even this, it's very much a "my personal tastes" thing, and many well-known level creators would feel perfectly fine leaving things the way you've done here.
The other two, yeah, I have to say I feel some work is needed on those visually. Don't take this too harshly - my early levels looked a lot like those, too, and I'm sure many other people would say the same about their early levels as well. I think the biggest thing is: With rough-edged styles like Dirt and Snow, the trick is generally that you don't just have pieces lightly touching like that; rather, you make larger clumps by placing multiple copies of the small clumps overlapping each other. (This doesn't mean there's never a situation that calls for using a single copy of a piece on its own, but it's rare compared to the "big clump" setup.)