A touch of art is always nice. This nighthawk fortress castle looks very appealing. I'd be tempted to build it just to look at it.
I'm still thinking of increasing hit points for the units. What about conscript at 3hp, regular - 4, vet - 5, and elite -6? It is not that much but will add great spice to combat. Another thing to consider is doubling all attack and defese values and making settlers cost 100 shields or more and 4 or 5 population.