If anyone tells you your brita water filter is silly and that their water, "Tastes just fine," show them this photo:
That is the whole-house filter from our home after just 3 months of use. Its original color was pure white.
Granted, we have a well and not city water, but still... You don't realize how much sediment and crap your water has in it. Even city water systems, while treated at the source, pick-up "stuff" in the pipes through which it travels to your home. Plus, a granulated active carbon (GAC) filter like the one found on Brita systems can remove chlorine tastes and odors that may be perfectly okay health-wise but are otherwise unpleasant.
For various reasons, we installed a whole-house filter system that consists of a fiber filter (the dirty brown one) and a GAC filter (the blue one). The fiber filter picks-up most of the dirt and sediment and the GAC picks-up odors, tastes, microscopic things, and even Radon, which we have a very small amount of in our well water.
Most homes can benefit from an "under the counter" or "point of use" filter on the kitchen sink. It's similar but doesn't require major plumbing to install. We had one in our condo and it was worth every penny.