while it would seem to work fine for a solo tripper, it seems like too much hassle to me for even a group of two - you can only do one liter at a time (or 1/2 liter) which would be convenient while travelling, but not so good for a base camp of several people.  I suspect the light intensity goes down quickly as the volume goes up till it becomes innefective, or takes too much time to work. 

so for 3 gallons say, you'd have to do 12 one quart cycles (as seems to be the case via thier user manual) --

which may or may not bother you, but I'd just as soon just pump the 3 gallons and get it done (or use gravity filter)

someone asked about batteries - the "classic" does use  4 AA