My experience with them has always been second hand, usually starting with, "Do you have a filter? My steri-pen stopped working." Last trip (Labor Day) two of the group had steri-pens (two different versions) and both failed. Fortunately the rest of us had filters.

The majority of problems appear to be due to using the wrong batteries or not reading instructions, but some folks are smart enough to use the right batteries and the instructions, and still have failures. So I won't be getting one any time soon. If it's not at least as reliable as the Hiker Pro, it's not worth getting.