Salt water Chlorinators are by far the most popular form of sanitising a swimming pool in Australia. We are in fact world leaders in this technology.
The process is quite simple. Electrons are passed from one set of cell plates to the other and they bombard salt ( NaCl or sodium chloride) on the way, splitting the Sodium molecule from the Chlorine molecule which in turn attaches to water (H2O) and forms Sodium Hypochlorite ( Liquid Chlorine). The end result is simply that you are making your own liquid chlorine.
Salt water pools run at approximately 0.4 to 0.6% ( sea water is 3.5%) salt content which is the same as human tears and sweat making it very comfortable to swim in.
Standard units use an Anode / Cathode cell and require cleaning once a month. The more expensive "self cleaning" units use twin Anodes and a reverse polarity system to keep the cell from clogging up, resulting in less maintenance.
TIP: Self cleaning units are definitely a better way to go and just because you don't have to clean them every month. The cells are full Titanium which should last longer than the old style Titanium / Platinum cells. Also be aware that self clean does not mean never clean. You do need to clean these cells once a year, depending on the Calcium and mineral content of your water. 10 to 1 Hydrochloric acid and water is the accepted method for this.
Most Ionisers are not recognised by Australian standards so be warned. It is not recommended to use any system that simply dissolves solid copper into the water. Whilst copper is a good bactericide it is actually toxic in too large a dose to humans. The best Ionisers are called Nature2, these use Copper / Silver nitrates held within a canister and they are NOT released into the pool.
Chemical feeders that have built in sensors are very good for those who don't want to know about having to worry about the acid and chlorines levels all the time. Just keep the drums topped up and the electronic device does the dosing for you.