I might be a bit late to the party, but here goes. This will be long, but I'm gonna bold the main points. Also, sorry beforehand, I didn't get to proofread it, so you can quote the bad grammar and laugh at it.
Buildings/Architecture:
The building style itself is nice - it's got the right balance of noise and substance.
However, there seem to be a lot of the same building. There's some variation in the
structure of the house, but I'd like to see some more variation in the materials
of the buildings, especially the walls and roofs. In screenshot 3, you can see a lot of this going on. Also, try to add more variation in the houses - the roof is a great way to carry over the idea that a building is from the same culture or architect as another, a trademark or signature of sorts, so try to vary the roofs a bit while keeping style consistent. Replace the outer part of some of the roofs with a different material (stone, and wood work great because of their neutral tones, but you can use other materials for that so long as they go with the color scheme overall). You could add lines of materials through the roofs (looks like a ribcage of the material hugging the roof). You could add chimneys*. You could add supporting bits beneath the edges of the roof, like fence or logs. As for the walls, try different materials and block types - switch cobblestone and stone brick for a few buildings, try other materials, etc. Be careful with placing wood near the ground because in real life, wood rots when it's close to the ground. Just don't go overboard with stairs.
Also, with that yellow [X] block, see if there are any other variations of the block.
One last thing, Screenshot 2: That chimney? Yeah, make it less. I'm sorry, I love big chimneys too, but they can draw focus from the rest of the building. I used to make all my chimneys 3x3 and hollow, but that means they're 3 meters wide. Thin it out a bit, will ya? The building isn't about the chimney. You could get away with emphasizing it on a forge or something, but that's another topic for another time.
Excellent, we have that sorted out. Now...
Aesthetics, Atmosphere, Structure/Realism
This is a bit of a broad range of things.
So I'll divide it up.
Buildings and Structures
Screenshot 3 again, check that small roof on the right side of the shot. It's held up by stone walls. However, be careful here, because there's nothing supporting that underneath. If you were standing underneath it, it would collapse, and 1 ton of shingles would crush you into dust. Also, the stone walls underneath it would collapse. Their base is the same width as their top. Replace the bottom block with a full block of cobblestone or lighten the weight of the blocks above it and replace them with fences or something. Screenshot 2. I'm assuming that's a windmill device? make that clearer or remove it. These buildings are right among a bunch of trees, and a lot of wind will get caught by those. So fix it. Also, that little bridge in Screenshot 2 won't do. I like how it's diagonal, but with diagonality (that’s a word now), you get a lot of jagged edges, which aren't great for aesthetics. Look up anti-aliasing. Same idea there. Either play off of that idea and make the edges less jagged-looking by making the bridge an arch, or straighten the bridge. Also, that building built into the mountain? Yeah, fix that. Make it less imposing against the mountain. Buildings can be big big, but mountains are massive. The scaling of the building should contrast with the mountain to make it look bigger. Downward screenshots or a more scaled-down building would do the trick.
Environment
Be careful with trees. Remember: wood is made from trees. There should be something to make it clear that a lot of trees have been processed - perhaps a lumber mill, excess firewood by the houses, or tree stumps nearby. Land had to be cleared and resources acquired for these buildings to be built, so prove it.
And grass. What's the deal with all the grass? Why is there so much? Sure, real life has a lot of tall grass in wilderness, but this is like a grasspocalypse. Ease up on it.
The stream - yes, I hate making streams too, but we all have to suffer for our art. All streams start somewhere (I think you made a spring for it?), and gravity pulls water downward. You see that cliff there? I want you to throw the water off that cliff and make an awesome waterfall. Lead the water into a lake or something afterwards. Also, water means plants, so feel free to put some more variety in plants around the water. Ferns, heck yeah!
Now onto the ground and other details...
That's a relatively small town. They have stone bricks and stone slabs littering the ground. Was that left over from construction? Decrease variety in the path, and get rid of a bit of that tall grass in the path while you're at it. Also, smooth out the path with some half slabs. It adds simple visual variety while smoothing something else. Nothing breaks immersion better than having to jump up a level every few meters.
See that random table in Screenshot 2? What's that all about? Same goes for the other one with the broken table. Change selection of wood on that, a table is better maintained than that and probably wouldn't have moss or vines. Also, what's the purpose of it? is it the loneliest market stand in the world? Is it there for a reason?
All that hay. What is its purpose, why hasn't it rotted yet, what is it being used as, and why does it seem to be taking over the world? Why isn't there a central storage area like a raised granary to protect it from insects, and how was it transported into town?
As for chests. Why do they need so many chests in that castle thing? Why are they not more secure? Why are there baby chests sitting in random places? Are they alive? Perhaps they're predatory chests closing in on their prey?
Now, travelling. How do people get into the castle, and why do they need that big gate? are there seige weapons, horses, or other things that need to be taken inside? If so, why is the entrance so difficult to access?
Screenshots, Textures, and Presentation
Bear with me a little longer.
You've made a product, now market and ship it!
The screenshots have too much lighting. Certainly there's depth in these buildings, but it's not showing with all that light. It looks like the world of Minecraftia is about to be cleansed in a fiery solar flare. Use lighting selectively. Light things you want people to pay particular attention to, and cast shadow on things that you don't want them to, or things you want to give depth. The textures, now. Is this your texture pack? There are some issues with tiling, especially with grass blocks. As for the dark wood, it looks a bit like brick with vines. Careful with vines and wood. Vines indicate overgrowth, age, and nature, which often go hand-in-hand with abandonment and rot/decay. Tread lightly here, because there's a remarkably thin line between a 'Fantasy' feel and an 'Abandonment' feel.
Now one last thing, back in the world of Minecraftia.
Throw in a couple novelty buildings. This means stuff like market stalls, fountains, stables, granaries, and even lamps if the population of the village is big enough or rich enough. Anything to add color and variety, to make it feel more 'lived in,' like there's actually a culture within the village perimeter. I think that about sums it up.
TL;DR
Just kidding, you’ll have to read the whole wall o' text.
