We have it connected to run to our fridge water line. Helps make the water taste better and no extra particles left in the glass when you leave a glass of water overnight.
Makes having clean, fresh drinking water convenient -- no pitchers, no clumsy add-ons to the kitchen faucet. Compact -- fits in a cabinet with very limited space. Read reviews about installation problems, but I found it extremely easy to install, and the kit included almost everything I needed in appropriate sizes. The only thing I had to buy was a large stainless steel fender washer, because the hole in my sink was a bit large for the supplied nut. My interior designer wife is very pleased with how the finished installation looks, which is a big plus!