For general "book" reading I think the cybook from WHsmiths takes some beating. It is light and very easy to use. I would prefer a form of directory support rather than just the library view as it ca take a while to find books if you loads of them, though probaly not much worse than most other 6" size units.
For reading pdfs from scientific/technical and other similar uses, the DR1000 is excellent, however it is at a very early stage in it's development as you may see from the forum & expensive. The stylus is a very useful addition, though full touch sensitivity would be even better.