Dark Ages in British Isles are fascinating, a dismal warlike time, in which people fight for survive. A dark age with deep blend of cultures. 6th and 7th centuries were a time when invaders (Saxons, Angles and Jutes) tried hard their destiny in a new world with the steel of their swords, shields and spears. Ancient people tried to resist, while they saw how their kingdoms are defeated and conquest by those “barbarians”, sorrowfully saw how his belowed world slowly disappeared off the face of the earth. Couldn't forget to talk about the Picts also, who have always inspire great interest. Or about West, other island, as complex as Britain, Ireland in which many people were fighting for a piece land, their clans, livestock and supremacy. In short, it is a world we know a little, but that it is like a magnet for history lovers: a time of war and great deeds, where few (almost none) kings died in his bed.
There's a difference between when a game is challenging and when it's so frustrating that it's unplayable. This, I'm afraid, is the latter. Granted, this is a wonderful concept and wonderful execution thereof, but this suffers from something I've seen a lot in mods that would be better than the vanilla, and that's the ridiculous amount of difficulty that, like a particularly bloodthirsty bully, allows you to think you'll come anywhere near enjoying yourself just so he can take everything you own and traumatize you more deeply. "Oh, look at your wonderful little army you spent the first few hours of the game working on," it says, "Let's see what happens when I throw a random group of bandits at it with three times the manpower." One needlessly complicated and ungodly frustrating fight scene later, your precious army with which you would convert the world to the love of Jesus Christ lies dead on the ground. MAYBE this is more realistic, and MAYBE the mod has wonderful features (everything about it, really, especially the naval batlles), but when it gets to this point, realism should be sacrificed just a bit and all those wonderful features will never see the light of day since you can't walk two steps outside a city before you're up to your neck in the corpses of everyone you love.
Bottom line: Recommended with extreme caution.