Hey Signalman,
If you want to connect to the internet via a cellular network, then you need the 3G. Basically, this is a feature you would need if you wish to connect to the internet and don’t have access to WiFi. You will have to get a 3G account through Verizon, AT&T, etc.
All in all, if you have WiFi where you are going to use the device most, I wouldn’t waste the extra money on 3G. I hope this helps.
Technically, this is incorrect. The Kindle 3G model always has a connection to 3G through “Whispernet”, which I believe is a contract between Amazon and AT&T that allows Kindle 3G models to use AT&T’s network without a contract.
In the last model of the Kindle (now called “Kindle Keyboard”), you could use the web over Whispernet. They got rid of this ability in the Kindle Touch, which means the only real benefit of the 3G model is that you can download books from anywhere you can get a cell signal, not just places you have WiFi access.
I have a Kindle Keyboard 3G that I’ve had since they launched last year, and I’m getting the Touch WiFi now. I’d say without the web capability over 3G, the 3G model is not worth it.
My advice: Spend even an extra $50 ($199 total) and get the Kindle Fire. It will do so much more, even play movies that Apple’s IPAD won’t play. And it’s a color touch screen.