I am completely addicted to my kindle, and haven't read this much since I worked at a library as a teenager.
It works beautifully for fiction, terrible for reference. So, it is going to depend on what you are going to do with it. You are able to take 'screenshots' with it, not in the manual, but info can be found on the web, which can be tranfered to your pc. The screen handles pictures rather well, along with a couple formats. PDF's don't work very well on it, but Calibre is a must have for easy conversion to a suitable format. With that, you can take any text you get your hands on and slap it on there. It will not have the chapter markers however, and you will have to place bookmarks manually. Lacks hyper link functionality, and navigation within a document is a bitch. But, if you are just reading something straight through, page by page, the thing is an absolute dream.
Works well as a manga reader as well, once they are converted to mobi, but it does take up allot of space. It's not like you are going to really be able to store a whole lot, and it takes about the same time to DL, convert, and place, as it does to read it on line. Works well for a short-ish series that you must simply always have a copy of around.