Product review (5 stars): Worth a tiny bit extra
The last time, we purchased a competing filter which is now being sold for a couple of dollars less than this filter.  After reading up on the certifications listed, I realized that the other filter claimed that it blocked 95% of lead particles and chlorine, whereas the certification that this one has seems to mean that it blocks -all- of those elements.  That, and the difference in mesh in the images (this one appeared more robust) made me decide to try this one out.

I'm glad I did.  The last time I bought the other filters, my fiance said that she still thought the water tasted a little "off" (I couldn't tell).  With this filter, she says it tastes pretty much like bottled water.  It's well worth the extra $2 to have that last 5% of chemical filtered out.  Even if it just saves you from buying one or two bottles of water in six months, it will have paid off the difference.

Just a word of advice:  read the instructions when you're installing it, and make sure to drain off at least 3 gallons or so.  When I first installed it it started gurgling and spewing forth brownish water--that goes away pretty quickly.