Each has their fans, but if you don't know where to start with regards to ebook reader specifications, lets have a little look at them in turn...

Don't forget that reading and using the Kindle doesn't mean you have to be online anyway. In fact yoru battery life will be almost doubled if you keep the wireless switched off! You only need to be connected wirelessly if you want to download new books direct to the device or synchronise your Kindle devices.
Now the main reason for using a Kindle to access the internet is to reach the Kindle book store where you can manage your account, buy and download new ebooks. Downloads done this way should get to your device within 60 seconds of placing an order which is pretty fast.
Of course you will need to know the password of any secure wi-fi hotspot you are using. But once entered, the device will remember the password whenever you are in that particular hot-spot again. Most of us will be using this at home anyway, utilising our own hotspot created by our home wireless internet router.
It is the same portable reader with the amazing battery life, and fantastic storage. It also uses the latest Pearl e-ink for the clearest display so far.
But it does have a little more flexibility as you can use the local 3G mobile network to access a few web sites including the Kindle book store. Be warned though you won't be accessing the web freely with 3G. Whereas when using wi-fi you can surf pretty much anywhere you like, 3G is limited to those sites that Amazon deem useful and so will pay for you to get too (namely Wikipedia and the Kindle's book store). If you want to do much of anything else online you will need to revert back to wi-fi. But since you have both facilities on this portable reading device that isn't too problematic.
Whether the extra $50 is worth the flexibility of ordering books using 3G from the beach whilst on holiday really depends on just how much travelling you do. If you have a wireless internet router at home, and don't mind only ordering new titles or synchronising your account whilst at home, I would save the $50 and stick to the wi-fi only model.
The Kindle DX reader is the Daddy of Amazon Kindles! With its mammoth 9.7" display it suits a more niche market than its smaller siblings. Much better for viewing large pages such as PDFs, newspapers and magazines it comes with the same Pearl e-ink display.
The DX Kindle has 3G which works globally, allowing you to access the Kindle book store and a selected number of other web-sites. Most importantly you can use the mobile network to download new titles in around 60 seconds from wherever you are.
Rumours include a Kindle color display, a touch-screen Kindle and even the possibility of a 7" Kindle tablet!
I wouldn't hold your breath though as there is no news on when a Kindle 4 release date is likely, and Amazon are saying nothing about what they might actually give us when future upgraded Kindles emerge.
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