Salt is Sodium Chloride. Basically a chemical combination of sodium and chlorine.
The electrical process divide the two and one of the by products is chlorine that is injected into your pool. The process is not 100% effcient so you will also get salt into your pool which will also help soften the water. That is why your skin feels soft when you get out of the water and you can taste some salt in the water. It is a good system the only thing you have to be careful of is what type of coping and plaster you use on your pool. Any natural stone that is layered, think sandstone, slate etc. is not a good choice for salt water pools. The salt water gets into the stone, drys and forms back into salt crystals and will seperate the stone. Also any plaster color other than white will be subject to geting white spots on it. A friend of mine's pool has sandstome hot tub flowing over a natural rock spillway into a pool with a blue plaster finish. The rocks are splitting and the plaster has white spots all over it. It's estimated it has done $10,000 worth of damage to the pool. His contractor that built the pool said nothing about his choices of material and did not warn him any thing like that could happen.
I think the system is great, I would just make sure it works with the materials in your pool.