[vivaldirules]

Almost none. I've tried to use my Sony Reader to read PDF technical documents and it doesn't work well at all unless you intend to read it from beginning to end. You can't search. It's not easy to get to another section and get back and then check the back of the book, etc. There's no color. The figures are hard to read. And you can't buy most textbooks you want. So what I recommend to all students who come here asking about ebook readers for textbooks is to do yourself a favor and forget it for now. Maybe it'll happen later but for right now, you don't want to cripple yourself by having to deal with a technology that will only eat up your precious study time. If you're serious about physics, study with the best tools you have available: physical textbooks. My opinion.