Product review (5 stars): Works great.
It's hard for me to get too excited about this item, since its just a little plastic holder with some activated charcoal filter media inside.  But considering some of the insane prices which appliance specialty stores tend to ask for just one of these, I'm grateful that there are places which can undercut them.  And they really do a great job of keeping the air smelling fresh inside the refrigerator; far better than any baking soda.