Here is a review that was done by HForHavoc on the mod.
It's a good review, hopefully it helps spread the word on this mod!
I just finished a long campaign with Northumbrya and have a few thoughts on my own. As always, it is my personal opinion and preferences, and I may have gotten something wrong.
I like the building system, the population mechanic, and 12tpy adaptation (finally the winter quarters are something you have to watch). Fyrd mechanic with Northumbrya was also really good, as is the food. Units are beautiful. It is fantastic to just look at the units and enjoy the variety of colors and shield patterns.
As for the skills system, it might in my opinion be too static. In more than 100 turns, my main character only got something like 4. So that part of the game could be made more dynamic.
My main concern is the public order. I never had any problems with it. Allegiance plays no part in it, so it never went negative (maybe for a turn or two in a fringe area). This makes the campaign more arcadey and I wonder why there are allegiance skills when allegiance is no longer represented in the game (or I missed something? Certainly didn't create any problems in my playthrough).
I don't know how HForHavoc got such replenishment rates, mine were much lower and usually I had great problems replenishing my armies, fighting with damaged stacks most of the time. I know population affects it a bit, but I have never run into manpower shortage anyway. Also, there were few armies on the campaign map. I fought maybe five battles on my way to long victory (short one was attained very quickly), and for the remaining time the map was pretty desolate and there were just settlement fights and catching single unit raiders.
I got all the messages about the endgame Viking raiders, but they never appeared, even after 20 turns? Are they scripted out or do I have to wait more?
As for the battles, I personally don't prefer the small units... Having 6 or 10 horsemen running around just seems funny. I'd double all of that, but that has obviously been set in stone. The battle mechanics are good, difference between militia and professional units is very noticeable, which is nice. Northumbryan hunters are devastating though, double the damage from normal archers seems excessive as the 18 of them rack up to 150 kills in a single battle.
All in all, the campaign was a decent experience with some pitfalls and many good mechanics, but I'm eager to see new updates to try it again!
The mod is still being worked on