[weatherman]

With the wireless off, I generally get a couple of weeks of use out of my Kindle 2, reading it for about an hour to an hour and a half every day. Keep in mind that the power usage is by the page turn, not by the hour or week though. So when you're reading manga, which generally has a shorter read-time per page (I'd guess) than a page full of text, you're going to be "turning" the page a lot more and using more juice.

I don't for sure, but the fact that it's in PDF format might make a difference too, since it might take more processing power to display that rather than just text. I've certainly noticed that it takes longer to refresh pages with pictures on them on my K2 than ones without pictures, which means that some sort of processing is going on and not all pixels are the same.

So I guess what I'm really saying is that the Kindle's estimated battery life is probably accurate, but only in certain circumstances such as reading a book of plain text from end-to-end. Throw in PDFs and pictures and it's going to vary by use.