A few months back I bought an e-reader. An IRex (DR800S) to be specific. This is my second e-reader, to be even more specific, because the Sony (PRS600) that I used before had an unfortunate accident. Although I occasionally use the e-reader to read books (not too often, though, I promised myself that I would not let it stand in the way of having pretentiously well-stocked bookshelves), my main use for it is to read academic papers. I thought my experiences might be of some use to anyone who is thinking of buying an e-reader for the same purpose.
Initially, I wanted to buy an e-reader with a small display, which are considerably cheaper than the large ones, and just scroll through the pdfs like you would on a regular computer. Luckily I didn't, because e-readers are way to sluggish to comfortably scroll through a document. This is because e-ink displays have a very low refresh rate (i.e., it takes quite some time for the image to change). Most e-readers have the option to reformat (reflow) text, which means that the reader tries to increase the font size while maintaining a reasonable layout. For books, which tend to have a fairly straightforward layout, this works fine, but for multicolumn .pdfs (i.e., most academic papers) the results are disastrous. So basically, if you want to read academic papers, you will want an e-reader with a sizable display. The IRex has an 8 inch display, which is just large enough to see the top half of a page and not having to do any sideways scrolling. My late Sony had a 6 inch display, which I thought was a little too small.
Many e-readers also boast the ability to take notes. In my experience, this feature is useless. Again, the screen is simply too slow, so what you see lags way behind what you're writing.
Nevertheless, I really enjoy reading papers with my e-reader. It is much nicer to read from an e-ink display than it is from a regular computer and, for this reason alone, I find myself reading more. You can also easily take your e-reader with you when you go for a cup of coffee, and get a change of scenery while at the same time getting some reading done. So I would definitely recommend getting an e-reader. I would even recommend mine, were it not for the fact that IRex technologies went bankrupt a few days after I bought it...
Photo: IRex DR800S
http://www.mobileread.com/ is a good resource for information about e-readers