Work on the grass a bit, especialy in the bottem part. Right now it doesn't look realistic because there's 3-4 tiles used to decorate the grass and they are too evenly distribuited.
River is too straight.
Underneith of your house looks like it was just put there, I don't know how to improve it using the current tileset though. But you might try using the tiles for the horizontial bridge where it meets the water.
Nice Ladder (sp?)
Trees in upper left have been chopped off.
Maybe add some watter puddles on the bottem shore line would add some spice.
Maybe adding another pice of land that connects to the northern shoreline but not as elevarted, (eg, same hight as house platform) with stairs, a table or place to sit, and some fencing, kinda like a place to sit and watch people go by
Overall, Very nice work, It's ready to go online IMHO; I give it an 8/10