I picked this up as a just-in-case gadget. I have now used it a bunch of times and it does it's job......at least I have had any intestinal problems from the fluids I've been drinking. Some reviews say there are loads of problems so maybe I've been lucky but I haven't had a single issue with mine. In my experience they do what they're suppose to and I'm happy with that. I initially bought the model w/o the solar charge but returned it for this one. I heard that people were having issues with the time it took the solar charger to get the battery's up and running but I didn't think so. It only took 2-3 hours from dead to fully charge, but maybe I'm lucky. None-the-less, this is a great addition to the arsenal.

My buddy's filter element froze up when we when camping out in a 10-degree Sierras weather. My Steripen kept working like a champ. I'm not sure that the instructions are correct though, it doesn't like to start in the water when I hit the button. I could only get a full cycle indication if I had it completely out of the water before I hit the button. Also, doesn't take debris or taste out of the water, just purifies it so you can drink it. Because its a purifier, not a debrisafier or tastefier. My only wish is that they could make the compact version, and still be able to use AA batteries. All in all, this is one of the first things in my pack when I head out.

The SteriPEN Adventurer Pen is perfect. Easy to use, lightweight, and easily a third of the size of the other water filters out there. Granted it's the most expensive water filter I've seen, you get what you pay for. Perfect for the lightweight backpacker.