The Nokia has color and is backlit (which could be an advantage or a disadvantage over the jetBook). I was very happy with my Nokia 770 as an ebook reader, using FBReader software, although I now exclusively use EInk devices for reading. It is almost exactly half the screen size of the PRS-505, with the landscape mode being the same width as the 505 (in portrait) but half as high. Since page turns are very fast, this isn't a big deal. There is a pictorial review/tour of the 770 at
FBReader screenshots.