I don't get it, people have been saying that they are essential but they require so much micro that you can't focus on much of you army. I like them but when you do a hit and run they run dead front and center of the enemy and shoot a volley and reload in front of the enemy! They don't even bother to run away. Then you would have to run them all the way back.
And even though they are very swift if used properly the enemy could just hunt them down with Hussars or Lancers and they are dead. They seems absolutely pointless since they only have the ability to run like hell when they are in trouble. And what negates against them is much more than their bonuses, such as: 45 men, 80 range ( it not really that bad but its not worth how many guys you could lose if mess up), terrible at melee or defense, require a lot of micromanagement. They have some good things as well, but I don't understand how could they be "essential".