I have to admit, after reading some of the posts I was a little worried about installing the unit. It was a lot easier to install than some people suggested. It took me about an hour only because I had to run to the local hardware store to pick up a long socket wrench. As for quality: I've had the units for about a month and the quality of the parts are impressive and the water coming out of the unit tastes really good.
We have had our Aquasana system for only a sort while so can't attest to longevity of system or filters but what I find remarkable is how smooth the water tastes and I tend to drink much more! I use it for coffee so that tastes better as well.