I love this game!! 220 hours in and still enjoying it immensely. Anno 1800 is the first Anno game I have played, and I didn't have too much trouble working out the complexities of the game. I only just realized how to get to the street level, so now I am just walking around my beautiful cities and islands :).
Meeting your peoples needs and working out the production chains is challenging, however there are lots of calculators you can find for free that help with this. Plus, lots of fun if you like math's and strategy! I didn't like War being declared on me and my cities, and upsetting my trade routes, so now I just continually do non aggression treaties. The details of all the different buildings are amazing, and some of the comments of your people are funny too.
Well worth the money!