I have the Steripen Journey. It has the LCD display with the smiling face, the timer, and the battery condition display, so there's no guessing about if the UV light is on in bright sunlight, if the sterilization cycle has been completed correctly, or if the battery is about to go belly up. I also use their Nalgene bottle filter cap, which in my experience works quickly and well if you follow the simple instruction to wet the filter membrane completely and open the airvent before sinking the bottle into debris-laden water. Then you treat the water with the Steripen and you're good to go. I carry extra batteries in the truck with the unit, but it has sat unused for weeks at a time without showing any sign of draining the batteries. The company has stated that the quiescent current is on the order of microamps (extremely tiny) when the unit is off and the batteries are left in it.

I also have a Katadyn Pocket filter in the truck as a backup in case the Steripen acts up for some reason. If you use the KPF unit intermittently, as I do, you must make certain to dry the ceramic filter element out thoroughly between uses in order to prevent any musty water taste in the future. The KPF unit is reasonably bulletproof, the Steripen is less so, in fact the battery compartment cover is somewhat flimsy, IMHO.