I frequently read fiction on my E90. As others have said the wide internal screen makes it a brilliant eBook reading device. And also as others have said, I much prefer reading on the E90 to reading a physical book.
Mobipocket do a pretty good job (although my aging eyes would like the option for a slightly larger font, just because the E90's internal screen insists on using a smaller font than the external one, which always struck me as odd).
Anyway, I have the background set to yellow with black text, which gives me the best setup for bedtime reading with the light off - clear display but without bright glare.
I like MobiPocket's slim progress bar at the bottom of the screen. I like the fact that I can choose my font and font size, text and background colour. I like the fact that I can use the space bar to "turn the page" (it's the most comformable key to use - much better than the D-pad). Lots of things about MobiPocket Reader just work well for reading a book. I also like the fact that I can make notes (albeit only by synching changes made on the PC end) about my books (give them ratings, write my own precis, make notes about what other books are in the same series, and in what order, etc.). For me, an eBook reader needs all these features, and others I probably haven't remembered.
Features I'd like to see on a S60-based app - whatever it's written in (i.e. not needing sync with a PC): the ability to add my own comments, rating, etc.; Library views showing both title and author (unlike a real book, you don't get a reminder of what you're reading every time you pick up the "book"😉 - Mobipocket gives you the option to open in library view (with the current book selected), but only shows the title, not the author). I read a lot, but often forget what / who I'm in the middle of reading. Maybe it's just me ...; the ability to categorise / tag / label books in whatever combination I choose, and view/filter the "library" by tag / label / category as well as by whatever built-in tag (such as genre) that the book is given by the publisher. It appears that if you change device, you also have to re-download secure (DRMed) MobiPocket format books, so it would be useful to keep a note of where you purchased too!
One particular book I read prompted me to look for more in the series, and I discovered that the next book was only available in eReader format (and later ones in no e-format at all), so I bought that, and installed eReader. It was awful. A lot of the formatting was poor on the internal screen (I don't even ever attempt to e-read on the external screen), with italics in particular not being rendered in the correct font size, and disappearing off the screen. It frequently seemed to "forget" part of my settings, so it would remember my font size, but forget how that related to page size, so turning the page would skip a couple of paragraphs. There was a poor (read uncomfortable) choice of keys for page turning so that I reverted to automatic scrolling which I don't much like, no option for scrolling part of a page, and numerous other annoying things I can't even remember. From now on, no matter how good the book, I won't buy it if the only option is eReader format ... unless I can find a better app that supports that format.
It may be "simple" to write a e-reading app, but there are still a lot of things that you can get right or wrong in the process that make a big difference to whether it's a pleasure or a battle to use it.
Then, I'd just like to see a much wider availability of up-to-date e-books! Bring on the latest Pratchett, etc.
Julie