It has two major drawbacks. One or better boith of them should be corrected.

1. One should normally be able to build units from the resources produced in its buildings. GPs are not resources produced in its buildings.

2. Its Persian positions should be corrected in a multitude of ways. 

a. They should provide some kind of benefit. As they are now, they are only a loss for players.

b. Persian Units should have a concrete and readily identifiable offensive and defensive value. What's with the "?" besides offensive and defensive values?

c. They are tedious. It is not only they cause damage, they are a ton of them. You need to do tens of them only to be rewarded by nothing.

d.There is no substantial  differentiation practically in the defenisve value of its units. They are all about the same.Homogenization ... meh!

e. It's missions are a major concern, as they can cause immeasurable damage to players, especially those playing casually and 

not willing to do even basic arithmetic.