I could be wrong, but doesn't this game(warband atleast) have a demo on steam? If not the next best thing would be some gameplay footage
I would check myself but I cant get onto steam with my internet connection. Unfortunately I can't compare it to anything as i haven't played a similar game. If you do decide to buy one of them, get warband. I dont feel guns really add anything to the game(added in fire+sword) and its quite easy to get killed by them.
The games graphics are quite dated by todays standard but its very enjoyable when you get into it.