I use it, must have read over 100 books with it; although I`m getting an Eee PC soon and that will become my main eBook reader.
Using a CPU/Bus Speed of 10/5MHz and a Menu Speed of 222/111MHz (can be set in Bookr`s options), I found that I have around 6-7 hours of battery time with it, although I used to have more (old battery). Bind both left+right arrow and
left+right triggers for previous/next page, this way you can flip pages easily no matter which hand you`re holding your PSP with.
Set it to a black background, cream/light brown colored text, use Arial as font and use the lowest brightness level, that way it`s good for reading in the dark. I have personally found that a font size of 16 and a line height of 110 are optimal for me, but obviously everyone should experiment and see what`s better.
More recent versions of bookr can be found here
, the 3.71 one works for PSP Slim as well. This version also supports DJVU, but I can`t vouch for that, I only use it for txt files; plus it swaps X and O, which I honestly like a lot.
It also has a Plain text - Wrap CRs option, but I haven`t really experimented with this, I usually remove linebreaks with MS Word.