Product review (2 stars): Test it for yourself.
Using a TDS (Total Dissolved Solids) water tester, here are the readings I got, you be the judge whether it is worth it.

Tap Water - 348 PPM
Dirty Filter - 330 PPM
New Filter - 270 PPM

So it filters about 20% of the dissolved solids in my tap water. Keep in mind my tap water is already safe to drink.