The Warpath Campaign. Some love it, others hate it. I personally highly recommend picking it up. It is a decent game and will provide you with tons of fun, provided you don't take it too seriously. It has a lot of faults, incuding random freeze-ups, lag, and an overall bad AI. But the Warpath campaign is not like the grand campaign. In the grand campaign, yuo could dominate the battlefield with a few untis of line-infantry and a couple of cavalry units. But in this campaign, there is none of that. Basically, all you've got are clubs and bows against muskets, cannons, and bayonets.
This handicap is what makes it so fun. You actually need to think out your strategy and use every advantage you have, because if you just charge forward with your infantry, you'll get gunned down and slaughtered to a man. You are forced to use guerilla tactics and make the most of your units.
As such, this DLC is highly worth it in my opinion, despite its numerous faults and defects. As long as you are relaxed and do not take it too seriously, this is the game for you.