Let me just start you off if you're reading this, by saying that this is a medieval game. The combat is medieval, real time, and not from an RTS view. Basically, if you've ever played a Total War game and have always thought about taking control of one of your guys in a heated fight, well this is probably the game for you.
If you're looking for high-end graphics, online multiplayer, an extensive storyline, all in a game designed by a well-renowned developer studio, then this isn't the game for you.
I was a little sceptical at first buying this game, but I actually found it more enjoyable and taking up more of my time than Call of Duty World at War did when I was waiting for Left 4 Dead.
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You begin the game by creating your own character, which has extensive settings for you to create your unique character in this world. You can then choose a backstory for your character which will play into your beginning stats. For the sake of this review, I'll be using my original character.
Here's about 1/4 of the game world from the highest perspective's point. If you've ever play a Total War game, this would be your "tactical map". Here you can choose where your character goes, be it through the country-side, to a city, to a battle already in progress and the like. As you can see, you have the options to..
Camp - Basically settling in one spot and while you wait time is sped up. You have a few options like giving the option to recruit prisoners to your party, choosing a book to read while you wait which will in turn increase your skills, retire from the game (to see how well you did overall) but the main idea behind it is to just wait. Over time soldiers/heroes in your party will receive experience just from regular training (albeit it not being as potent as actual combat).
Reports - This is basically your go-to for when you want to see your standing in the world. There are five different factions in the game, all kingdoms that really only vary via units/strategy implemented through combat. It will show your renown (basically a stat that is only rewarded to you through battles where the odds are against you, the higher your renown the higher your party's morale will be) as well as your standings (-100 through positive 100) with these factions are. Generally if you're at war with them, they hate you, if you're an ally towards them, they will be loyal towards you.
Quests - These are basically what they sound like. There are various Lords in the game. They act like medieval day's Barons. They are the only people in the game that are able to raise armies under a single banner. The Lords will serve under a King, which basically makes up that kingdom. A kingdom is nothing without its kings/lords. Anyways, you can ask Lords if they have a task for you, and then these quests will appear in your Quest log. Basically like any MMO you've ever played. 
Inventory - This is important, because not only does it show what you're wearing, but it also shows what you're carrying (basic stuff, amirite). This is important, because in order for you to survive you're going to need food. If you want people to follow you and fight with you, you're going to need to get more food. Food is easily attainable pretty much at any village or any city.
Party - This is the party screen. Here you can see who's in your party, including heroes (named soldiers that have skills), regular soldiers, prisoners, and of course yourself.
My character's name is Arthael. I have a few named characters which are more effective as they level up than any other unit in the game (willing you equip them with decent gear, yes, you can equip them much like yourself). I didn't just pick "anyone" though. I have two combat-oriented members, Firentis & Lezalit, a medic, Jeremus, a trader and finally a tracker, Marnid and Borcha respectively. They all have their own personal skills that can be levelled, much like your own. This is useful, because there are plenty of skills that are considered "party" which benefit the party as a whole. Since your character can't be the best at everything, simply because as you level it becomes increasingly longer to level up again, having these other character specialize in certain fields like being a surgeon or a tracker, makes your party more efficient by tenfold.
But, this is all just numbers and boring stuff, right? I mean, the title's called "Mount & Blade" so let's get into the combat, shall we?
Right now I'm a Lord with a fiefdom to the Swadia kingdom (Orange Text Territory) who is allied/neutral with all of the other kingdoms except the Vaegir kingdom (Green Text Territory). So, here's myself about to assault the castle of Radoghir. I've been at war with the Vaegirs for some time, so I've shrunk their territory down exponentially, so of course they're running out of vacancy at their castles. ;P The odds are little against me, considering I've only got 30 or so soldiers, but given the fact it's on the easiest settings and I have the best soldiers my kingdom has to offer, let's put our mettle to the test, shall we?
Well it wasn't long before I had forgotten that I had already made peace with the Vaegirs, thus making Swadia a lot like Sweden. Well, for the sake of this little review we'll go around slaughtering Vaegir Farmers. Maybe that will make them a little angry.
Wow, they died ridiculously fast I could only get two combat screenshots. lol
So anyways, it would seem that the village from once those farmers came, did not like that I slaughtered innocent peasants from their village. They were now hostile too me, so I decided to go and plunder/raze their village. Since I had quite a following with me, they gave in. This is me looting their village free of charge. (Note: Selling this at a local city gives you quite a bit of money. Granted it's the way of the bandit, but it's very profitable.)
Now that I've successfully angered the Vaegir Kingdom, it's now time to beside Radoghir Castle.
One built siege tower later, and it's time to scale the walls.
Or, not. It would seem that Lord Doru has decided to ride out and meet our calvalry that's besieging his castle. The only way to settle this arguement is by the blade, since for me surrender is not an option.
Alright, so the only casualty that occured on my side was Jeremus, our medic ironic enough. Their entire force was wiped out (given easy settings) and finally the assault on their castle has begun. Instead of hiding on their walls, they sally out to come fight us face to face.
The battle is won in our favor. Now begins the siege.
The siege tower to our left will help us assail the walls. Of course we're pelted by arrow fire and the like, our soldiers stand strong. For the defenders, this is no longer about honor but a matter of life and death. If we breach their defenses, the survivors will be slapped in irons while the lucky ones will pass on to a better place.
I'm the first person going into the fray, ready to cut swathes of my lightly armored foes.
With the walls cleared of the Vaegir archers, the remaining soldiers nestled in the castle have come to retake what was once ours.
Finally, the keep is ours.
The enemy Lords sing our praise.
Since he is a viable enemy in the future, I will keep him under lock and key. One less general I have to worry about. Finally, the castle is taken for the glory of Swadia.
That's the magic of Mount & Blade.