Yes, they’re very much worth the purchase. Petzl’s Tikka ($35), for instance, runs for close to 30 hours on three AAA batteries, and puts out plenty of light for camp chores, reading in a tent, even some night-hiking if you’re a little careful. And of course it’s extremely compact, and weighs only about 2.5 ounces (a lot of “traditional” headlamps weight 9 to 10 ounces). New this year is the Petzl Zipka, which has an adjustable and retractable strap so it can be attached to almost anything-arm, helmet, whatever.
But LED lights aren’t perfect. As with all things there is a tradeoff. They emit a sort of bluish, otherworldly light, which takes a little getting used to. Moreover, they just aren’t a good ol’ light cannon like a Pelican Pocket Sabrelight ($28), which uses a Xenon bulb to really throw out some candlepower. Of course, with its two C-cells and bigger case, the Sabrelight also weighs three times what the Tikka does. For that reason, some people opt for “hybrid” headlamps that utilize both traditional bulbs and LEDs. An example of that would be Black Diamond’s Space Shot headlamp ($60). It has a Xenon bulb for when you really need some light, but uses six LEDs to conserve battery life when doing things such as washing dishes or reading.
Still, for general-purpose use, I think LED headlamps have reached the point where they’re the only lamp many campers need.