I've been glad I got the 3G version a million times over.
The 3G was a godsend on a 2 week cruise because everytime the ship docked somewhere, I could use my kindle for emailing (gmail works very well) getting news feeds delivered and browsing my favourite sites. The Kindle browser isn't great - but it is adequate enough for emailing and many text-heavy websites. It saved me paying for the very expensive onboard wifi.
We've also had a lot of problems with our wifi connection at home. My Kindle came to the rescue again and I even used the Kindle to purchase some lightening deals in the Black Friday Amazon sale. While many other people were complaining that you needed a fast Internet connection or a mega computer to get hold of anything! Well the Kindle managed just fine
So, for me, it was definitely worth paying the extra. But I can understand that if you have a better alternative, you probably wouldn't
choose to use your Kindle web browser. It works but it is a little slow and can be difficult to navigate some websites. But if you travel abroad it can definitely save money over using a smartphone for instance. And, here in the UK, we're not exactly inundated with free wifi hotspots except for McDonalds.