Just a couple of questions about this device.
How do the PDF's or Word docs come out on it? Are they clear?
Not bad but not optimal. A PDF is basically displayed on full screen. There is no way of increasing the text size other than zooming in on a section of the document. Best thing to do it download Calibre and convert said DOC of PDF to a MOBI file.
On my iPhone I like reading some of the linked articles on Twitter but of course it's a strain. Is accessing Twitter easy on the Kindle?
The advice I have given my mates is not to rely on the Kindle to access the web. There is an experimental web browser but it's relatively slow to load pages and because of the screen technology (refresh the screen for each page load) it's not ideal. I would reply on it as a backup web surfing device, personally.
3G or Wi-fi? Does it make any difference with the 'sync' i.e. when you're on the move?
I went for the Wifi version for two reasons.
1. I can tether my Kindle to my Android phone for free.
2. I'm not that bothered about buying books on the go, I load it up in advance using my Mac.
Depends on what you'll use it for I guess. The syncing is no different though, it will sync when you have access to the Net, whether this be via Wifi or 3G.