I like the concept, and found the first hour fun to play. After that, a number of things combined to make progress less fun:
1. Some way to delete buildings would be great. My screen was getting cluttered with mistakes I made before I better understood the game.
2. Progression based on # of days played was annoying. I was just starting to get the hang of things, and then more colors and nodes pops up. I agree with max pop idea mentioned below. For example, I never had a natural chance to explore the demand buildings (what do they do? no idea - need to get new goods to feed the population!).
3. Toggling workshops became annoying by the end - it became an action game instead of a strategy game, because I need to move the mouse to the left without touching any other nodes.
4. I was unable to get an owned dual producing workshop to continue working until I set both goods to on and supplied the needed goods, which didn't make sense to me (and thus took me a bit to think of).
5. A way to see all of my trade routes at once would be cool.
6. Agree that the different nodes need to be more distinct - the colors really start to blend once there's so many.
7. A way to force a buy on a market or let a workshop stockpile would be great. (I want to be able to have a trader moving back and forth all the time, regardless of demand - as it is now, the trader needs to wait until a workshop is ready to buy, but that's silly - the workshop should be able to stockpile).
8. A progress mechanic based on total global pop would be nice - as it is, I really only had 1 'city'.