As the creator of the board, I've been in most of the games, and watched most of the rest.  Here are my conclusions about how to play it.

#1: Take the bonuses at the top fast.  The effort pays off quickly.  And you wind up with much more easily defended territory.

#2: Defend in depth.  I've not seen high walls work well.  Because, particularly once cards come into play, people break through those walls.  And the size of the wall relative to the bonus is not very good.  But it is easy to devote a certain fraction of your production to building up reserves, and those come in handy.

#3: Pay attention to who is around you.  Everyone naturally expands down and out, so you have inevitable collisions ahead where both have only one natural place to go.

#4: Individual personalities matter.  There are no natural barriers, and all points are pretty closely connected.  Therefore the exact interactions between people can really change what does and does not work.

That's what I have figured out, and now you know how to beat me. :-)