I really like the concept of this game. Banner saga introduces several new genre elements:
1) Your damage output depends on how much health you have
2) Decisions you make between battles can be life and death for your characters
3) Turn order changes based on the number of remaining characters on each side
I think 1 & 2 are really awesome, but 3 detracts from the experience for me. Instead of trying to kill your opponents, each battle is a struggle to keep as many enemies alive as possible, but with only 1 - 2 life remaining, so they can't do any damage. If you kill an opponent, then the remaining enemies move up in order (essentially getting more turns), which means if there is a powerful enemy in a battle, then by the end, they go every other turn. Enemies like Bellower that heal on their turn make this mechanic even more ridiculous.
If they make a banner saga 2 or come out with additional content, I hope they consider using a standard turn mechanic, where killing an enemy is actually favorable. Also, the map gives the illusion that the game is an open world with lots of travel options, but you are given very few opportunities to make travel choices; I'd like to see more variety in travel.