I'm finding my big complaint about most PDF releases these days is excessive graphics in the visual layouts. HotB is no exception.
I read (and these days, run) most of my games off of my ebook reader. (Sony PRS-505.) This device has several limiting factors... 16 grays, 6" diagonal display, slow low-power processor...
Heavily graphic pages take forever to render (up to 10sec for HotB, and than only between pages 2 and 20), and further, when reflowed, the background images result in lots of page turns before one finds the text.
I don't mind the small page size, and the font used in HotB is readable. but the 4-10sec page turns...
So a low-graphics edition is my suggestion, perhaps even a specific ebook-reader edition in Acrobat eBook, MobyPocket (.prc) or Sony BBeB (.LRF) format.