It's a fun game if you give it a chance. First off, there's no story. You go from town to town, either excepting quests, trading for profit, entering fighting tournaments, etc to earn money.
You can then build up an army for whenever you enter a battle with another group of NPCs. This is the best part of the game, as the horseback combat is very fun.
There also a multiplayer open beta, in which you can enter your Mount & Blade serial. Multi can consist of battles of up to 64 players. I only played a little, but it seems you get gold for more kills, and thus can equip yourself better the next time you spawn.
Overall, it's worth $5, but not the full price.