These irregular troops are often poorly equipped and ill-disciplined, but they can be a very effect, mobile "mob".
Such men have little to do with standard military protocols and practice, or even organisation, often taking up arms in extraordinary circumstances. This lack of discipline means that they can sometimes be extremely brutal, even brutish, in their behaviour. This can work in their favour, in that it gives enemies pause for thought. More typically, their lack of discipline counts against them, and faced with a well-ordered force they can be at a disadvantage. In such a case, their mobility can be a boon, allowing them to harass an enemy and withdraw as soon as the fight goes against them.
In the vanilla version of Empire: Total War, Azzars are the only light infantry substitute available in the early game to the Ottoman Empire. However, with the Elite Units of the East DLC, the Ottomans gain the opportunity to train Haydut Irregulars and Bosnian Panduks, both superior to Azzars. However, these units may only be trained in Bosnia, while Azzars can be trained anywhere with the proper facilities. Therefore, Azzars retain some utility for the ease with which they can be recruited throughout the world map.