I have some feedbak, nothing major, but I would say that a professional designer could help you improve the book cover. Right now somebody with professional experience in graphic design --or a good eye for design-- can probably see details in it that could be improved. It's a pity if you have worked on this for five years, not to present it in the best possible way.
Definitely don't worry too much about it. I did not want to sound negative, it's just the first thing that came to mind as feedback. I haven't had the time to read the book, only had time to look at the cover, haha. :D
When one learns about graphic design, one ends up obsessing about these kinds of things. "These text lines need a tiny little bit more of space"... "Those margins are slighly too small"...
It's just job conditioning... At some point in my life I was playing the game of trying to recognize the fonts I was looking at in the adds and signs as I walking down the street.
I know. And frankly, I'm not even the worst coder when it comes to graphic design. I know enough to see that _something_ is off with the cover, but not enough to figure out what ;-).
There are some details about the typeface, layout, and the photograph that, as somebody with a certain background in graphic design, I can perceive as a little bit off.
That's all right. Focusing on the cover's photo, for example, I think you used a photograph that you had around. A professional designer working on a cover would (hopefully) shoot a flower on a studio, with professional lightning equipment, arranging the light sources in a certain way. I mean to get the final result of the kinds of covers I linked to earlier, which to be honest are exceptionally well designed covers!...
Those are the kinds of details I was referring to. On the other hand, many computer science covers have historically been quite poor in terms of design, and of course that does not mean much about the quality of the book itself. Some poor covers became memorable and iconic. Some covers are really simple and yet effective like the O'Reilly covers which I particularly like.
Sorry this is going on a tangent unrelated to Lisp. I do like the design of the book cover with the elegant white background. Thanks for writing it, I can't wait to read it.
One thing you could to do the cover to immediately improve it is add margins to the title text, especially to the top. The subtitle is also too long, "ever created" is superfluous. And you shouldn't capitalise the H in history; either make the whole thing title case, or normal sentence case (we don't capitalise nouns or use capitalisation for emphasis in English).
Disclaimer: I'm not a professional, but you did ask ;)
