I like mine. I have the Classic, first gen model. Had no problems. I used to prefilter moving water with a bandanna when that prudent, but now have the FitsAll filter.

The important thing about the Steripen is you have to press the pen On button before putting it in the container or it won't work. You then put it in the container and the level of water has to reach the electrodes or it won't work. Then swirl the water a little, light goes off, good to go.