I recently downloaded and played (after many erroneous installations) the mod (with patch C) on chieftain, to get a feel for it.
so far this is some of the feedback:
at easy difficulty, I've managed to defeat those I was at war with quickly enough for them never to get any decent characters. when I wanted to get into the circle with the demon in it that you can only enter at level 15, I was sad to find my best character was level 14, and couldn't find a way to gain experience anywhere.
which brings me to another problem I've encountered: in an effort to gain levels anyway, I wanted to remove the peace agreements I've made, and war with another faction in the hopes of finding opponents strong enough to provide me with experience. somehow I couldn't find a way to remove the peace, nor attack through a betrayal.
I usually thy to win through cultural victories. now, I've bought CIV 4 directly before installing this mod (and because of it) so I don't know whether you have to turn it on as victory condition, but with several cities at legendary culture, I still did not finish the game. perhaps a greater variety of victory conditions is possible?
and lastly, somehow, I could not get as much cities to join my side as I expected, which I usually do get, again, because of the culture. it might be an issue with following a different religion? however, the amounts of culture where pretty large, to the point that some of my borders partly or even nearly completely enveloped the borders of a village from a neighbouring faction. so perhaps a balance is on order.
other than that, I enjoyed it so thoroughly that I noticed the birds had already started whistling and the sun had come up again when I quit.
I hope this feedback is what you are looking for. this whole thread was TLDR.
Edit: you may not be able to enter that circle before level 15, you c an certainly cast spells like meteor on it. (guild wars images for spells might be problematic when PlayNC or Arenanet gets wind of it too)
Edit: I managed to cast my world spell twice in the game, don't know why. (change tiles to hills)