Hands-free — the ability to use both hands is a major advantage over a flashlight, and for certain activities like climbing, hands-free is imperative. Even around the campsite where a lantern can provide general hands-free lighting, the ability to easily direct extra light wherever you'd like, with just a nod of your head, is an advantage.
Beam Distance — This can be a big asset for finding things in the dark, such as the poorly marked trail back to your car or campsite and helps avoid falling over any dead bodies or running into serial killers
Compact and Lightweight — they are easy to fit in your pack, and the lightest weigh less than an ounce.
Durable — many of the higher quality lights are built tough, offering water resistance sufficient to operate in sustained rain storms.