Well...
The gist of it is, you create your mercenary and you hire your own little squad units that you can take into battle. The nice thing is, you aren't obligated to one side. You pick each battle yourself, and you can go by whichever country you like, whichever battle pays more, etc.
I'm a huge fan of the action system for combat that they have going on. I'm glad it isn't turn-based, and you still get control. The squad types are pretty amazing. I know it's very mediocre and bland, but my favorite units are the sword units (which I'm level 40 in XD). I want to give the horses a chance eventually, too.
I'm not sure how historically accurate all of the game is, but if you are anywhere familiar with the topic of the Hundred Years' War, you will see familiar faces such as:
France
Joan of Arc
King of France (Philip VI)
Gilles de Rais
Gertrand du Guesclin
La Hire (Étienne de Vignolles)
Philippe Le Bon
England
John Chandos
Edward, the Black Prince (Prince Edward)
Hal (Henry, future King of England)
Henry Percy
King of England (Edward III)
Anyways, I think this is a great game and it has a lot of potential. The battles are pretty epically scaled, and there are tons of maps, giving you somewhat different fighting environments, including Normandy, Brittany, Flanders, Gascony, and Champagne - just to name a few.
My Overall Rating: 8 /10