In dev review - Yes, the M&B series isnt perfect, there is some level of jank, but it is the best medieval simulator you will ever play. For those unfamiliar it is a combination of RPG, strategy, and management game in one with amazing action combat. You begin with some companions and build a party to become a mercenary, a criminal, a trader, a lord for an existing faction to climb the ranks, or even make your own kingdom and become king.
There is a world map where your party is represented and you move about to get to towns or castles and encounter other lords or criminals. You can interact with them, or battle which then moves into a battle map and you lead your troops. This time around they even added clans, which you form your own house, and other features such as blacksmithing. If youre in to RPGs or generally medieval times I would highly recommend it, watch a video or two and check it out. On top of an amazing medieval sandbox there are also some of the best mods. Right now they are in their early stages, but just check mods like Between Empires (19th century Europe with guns and cannons), The Last Days of the third age (LOTR total conversion), or any of the game of thrones or mods for warband.
Bannerlord not only drastically improves and modernizes the graphics and sound and is a general great improvement, but also adds many features. With blacksmithing you can create your own weapons or sell them for money, you have your own clan to manage with relatives that can join your party or govern your castles and towns, much more advanced battle commands system, you can have children that will take your character's place when they die in combat or from old age, can start your own trade caravans, buy and start businesses in towns, start war parties led by companions, and so much more.
Again, just check some videos if you are at all curious. The Mount and Blade series is the kind of game I waited my entire life for and Bannerlord is a vast improvement!