Product review (5 stars): It's like getting all new dishes!
Before we tried this, I used to have to pull out all our dishes twice a year and spray them with Lime-away to get rid of the white cloudly glaze on everything.  Our options for a whole-house filter were limited by the placement of our supply lines, so we tried this filter instead.  It took less than an hour to install, and it not only prevents the hard water cloudiness, but a few cycles in the dishwater and all the existing cloudy dishes come out sparkling clear.

I waited a few months to write this review to see how long the filter would last.  I bought a set of water hardness test strips to make sure I'd know objectively when the filter stopped working, and tested a bit of water inside the dishwasher and from the tap every month.  I got somewhere between 2-3 months from the first filter (the third test showed both test strips the same color).  At about $16 per filter (4-pack direct from manufacturer plus shipping), that works out to a little less than $8 per month.

Keep in mind that this also keeps the dishwasher's spray nozzles from clogging as often, because the mineral build-up affects your dishwasher as well as your dishes, so this is a pretty reasonable option if you have hard water.

Be sure hard water is actually your problem before you get this filter.  Take one of your cloudy glasses and scrub it with a sponge and regular detergent.  If that does work AND Lime-away or CLR clears up the cloudiness in seconds, then you have hard water and would benefit from this filter.