Nearly identical is Petzl's Tikka Plus, another LED-based light with an all-in-one light and battery compartment. It costs $38 (www.petzl.com), and boasts three brightness levels, strobe function, three AAA-battery requirement, and all the required weather armor.
Both the Tikka Plus and EOS are pretty much state-of-the-art, tried-and-true LED lamps. But some really interesting things are happening in this sphere. Petzl's Myo XP, for instance, is a $70 light cannon that uses a single big LED to throw a beam of light some 200 feet. And it has a "high output" phasethink of it as combat boost for headlampsthat can put out even more light for 20-second periods. It's water-resistant, uses three AA batteries (so is a little heavier than other lamps mentioned here), and has a helpful battery indicator.
One last worthwhile choice is Princeton Tec's Yukon Extreme ($70). It's a dual-mode light (Xenon bulb or LED) that uses eight AA batteries for lots of light and long life. Great news here is the battery pack can be stuck anywhereclipped to your belt, put in a small fanny pack, whatever. So you have only a light strapped to your head, and the batteries can be kept warm and dry, where they'll function best when it's cold. Worth a look.
Check out the Outside Gear Blog for a review of Princeton Tec's EOS.