I've spent near enough two good solid days in this game, and first of all let me say what a fantastic job you've done: Everything looks incredibly promising thus far - there's a definite feel of Ultima Online meets Harvest Moon meets Dwarf Fortress.
Now then, onto the downers I've noticed so far, even though I'm aware that probably more than half of everything I mention is likely going to be something that's already planned or even in development.
No way to domesticate animals
At the moment, theres no way to maintain a flock of nearby animals, which makes anything animal related somewhat difficult - expecially leatherworking.
Food requirements
It seems my character needs an absolute mountain of food in a day, and apples in particular seem to provide a bizarrely low amount, requiring 50+ just to fill you up for barely half a day.
Cart movement
Carts seem to have rather large collision boxes, getting stuck on all kinds of things. Getting one through a two-tile wide gate is often a complete pain. Reduce the size of the collision box.
Mining and smithing unrewarding
This is one of the big ones.
There is little to attract a player to things like mining and smithing. The LP outputs are noticably lower than those from the farming related skills, and ontop of that, failure rates are incredibly high - mining out 25 tiles to get usually 2-3 cast iron is a little depressing, and this is made even worse when you get to trying to produce wrought iron, where you have a 50% chance of trashing your iron, and then even if you make bloom, you still have a 50% chance of failing to make wrought iron and ending up with cast iron again - which puts you back at your 50% chance of becoming slag.
And to this the fact that you need charcoal, and you find that the industrial side has it a rather rough. I suggest Increasing the percentage chance of getting cast iron from the smelter - the failure rates on refining it to more valuable materials wouldn't be so soul-crushing if it were easier acquire simple iron, which isn't used for the construction of all that many things anyway.
Mines quickly become enormous
This is somewhat tied to the above, due to the huge amounts of ore required for even a single bar. A way to slow down the physical expansion of a mine is to give 2 ore per tile, and double the time taken to mine a single tile. This would mean that mining ore wouldn't be any quicker, but you wouldn't end up with huge empty caverns within mere days.
Combat is clunky
This is sort of double-sided.
The current combat system is somewhat awkward. In a way, I suppose this may actually be a good thing as it makes attacking other players less appealing, and I get the feeling that in this game, war and murder are supposed to be ugly things that are unpleasant but sometimes necessary rather that a definite focus.
MOVEMENT
There has GOT to be a better way to move than having to left click the ground every 2 seconds. Either via keys or via click-and-hold to move towards mouse cursor, UO / Diablo style. The game is click-heavy enough as it is.
Resolution
I'd really love to fullscreen this thing. It'd be nice to see further (although I imagine this could affect bandwidth and performance), but even just fullscreen 800x600 would be good - everything is damn tiny at 1600x1200.