It took a few tries but I started getting the hang of it. This is definitely a turtle-ing game, not an expansionist or economic game. The boss trolls were a bit difficult to deal with, I only had two builders and dozens of archers but they crushed my force easily. I don't think the basic trolls should increase in difficulty to kill if you are unable to increase the effectiveness of your weapons. Until that last wave, I was successfully defending the second set of walls in each direction, so it was a bit frustrating to be creamed so quickly. The continue feature is pointless, since starting with no money and no troops just makes it more difficult than it already was. I would have enjoyed it if the upper limit on the keep was much, much higher.
I really like the effects, the different weathers and the rippling water effects especially.