I've liked the books I've gotten from them (usually from Reginald) and will definitely get this one.

Fun fact - I remember meeting their founder (Peter Armstrong I think) at RailsConf many years back. He had just written "flex on rails", which was a great book (though both those technologies are unsexy these days). He mentioned his idea for something like LeanPub (though I'm not sure how far along he was at the time).

Great seeing him/them execute on this and become the de facto for self-publishing.