Product review (5 stars): Great product.
I buy four sets of these every year for winter.  Yes, it seems pricier in the long run to keep buying filters instead of humidifiers that don't have filters, but I've ended up just throwing non-filter humidifiers away from the icky water build-up.  And I love the humidifier.  Our house is very dry and my son tends to get bloody noses, so the humidifier runs 24-7.  I change the filters about every 6 weeks.  Never had a problem with these.  I'll be buying four more next winter.