Those geniuses at Google have also solved the problem of loosing your internet connection. They refer to this as "offline access", all you need to do is install Google Gears, and it is done by "cloud computing." Microsoft feared this feature so much that they came up with their own version, but it is extremely slow and you need the expensive Office software in order for it to work. Googles version is fast, with minimal delays.
Compared to other popular spreadsheets like Excel and Calc, it is somewhat basic, but I think it is good for the average persons needs. Features are constantly being added that are based mostly on user demand and it has advanced quite alot since its release. If you need help, you can search Google Groups which has all of the answers to most problems plus Google Docs has a good help page. Google has yet another hit software product.
Google Docs Offline Access