I do, and I'm sure many others here do as well.
Mine is just a singular relatively inexpensive "home depot" variety, and our water here is quite hard, to the point that things scale up quite quickly here.
As for filtering, yes, it seems to do that well, as after about 5 months the filter was getting a bit dirty looking.
I might be getting some small benefit, as on occasion city crews are ripping up municipal water lines, and much sediment often occurs. As a side note, we do not drink, or cook with the city Tap Water, as we think it is that bad, and unhealthy.
But as far as "softening" the water, I suspect what I use does little to nothing as far as changing the water's pH.
Somewhere on this site, there are filter cartridges that are sold which claim to actually soften water, and fit these small cannisters.
They are relatively expensive, and am unsure of their effectiveness, and how long such a small cartridge filter would last?
Perhaps others can personally comment, or perhaps point you towards some threads in which there are comments about this particular type of Filter Cartridge?
Mark