Wil,
I have never used one but I have met and spoken with the creators at some outdoor industry events. It is really a great method of cleaning water. The only think you need is some sort of strainer to remove solids and I think they have a kit with one included. It works great for small quantities say 1L at a time and you can also do larger quantities by hitting the button multiple times.
I think they retail for $150 and sometimes you can find them for $99
I was always tempted but never bought one. Enen though I know it works I think my brain needs to see the mechanical system working like in a traditional filter!
I would get one if I found a good price.
There are a few others on the market using UV --- and I believe some large city water departments, like Chicago, use UV to purify the city water.