I have had my system for 8 years, my 1st review is 2nd to last in the review list, and I have no doubt it will continue to be the best part of my house for the next 8 or even forever.
Over the years I have replaced filters on average 8-12 months. Full size house with family of 4 and 3 bathrooms.
Some changes from the early years that I miss though, are the clear housings and exposed filters. I really like watching the 'inside' of the filter change over time. Just seeing what was being stopped by the Pure Effect was awesome. I think from a engineering view though, the new style filters are better. Even if you can't watch them get dirty.
This is the single best investment anyone can make to their home.