If it's anything like how Jack plays in Horde mode, then he's a great support character. Has more mobility than the other characters and can buff/shield teammates while also being able to harass enemies without necessarily being able to kill them outright like standard characters can. Jack in Horde mode also has the ability to take temporary control over an enemy so you could control a potentially dangerous enemy and use them against the others.
Basically a more "easier" way to play through the campaign without having to play standard Gears with all the aiming and stuff should you want a slower pace or if you're just new to shooters/Gears.
