I like the Berkey units, but there are a number of people I respect that recommend the Katadyn Gravidyn. The berkey is the only one I have personal day-to-day experience with, and it's been fine. There was a bad run of bad berkey filter elements, but that's been several years ago.
Water from my wife's parents' new well couldn't be used for anything that involved heating of the water. It wasn't toxic; just nasty tasting if it got heated up. Making coffee, tea, cooking in general, the water took on a funky bitter taste that wasn't there when drinking cold from the faucet. The county extension office found nitrates & iron in it, but couldn't definitively say what specifically was causing the temperature-related nastiness.
For several years, they used bottled water for drinking & cooking purposes, but in 2011 my wife and I bought them a Big Berkey for Christmas and it totally solved their problem. I cleaned the original two filter elements twice over the years, and finally replaced them this past fall at four years old.