A lot of the times an item such as Steripen gets a negative review is simply because of "user" error.

One common mistake is when people use alkaline batteries instead of lithium or nimh batteries. Alkaline are not recommended and will quickly die after only a few uses. Lithium is the battery of choice for all Steripens.

It amazes me how many people simply don't read directions.

Also, I believe only the Steripen Classic comes with a prefilter that fits most wide-mouth bottles. The other models don't include a pre-filter.