This trilogy was lots of fun, and can be read as a big space-adventure in an alternative history Earth, with nazis, aliens, and lots of raunchy NSFW scenes. Do store it on a higher shelf, out of reach of children.
Familiarity with the author's personal history, philosophy, and other non-fiction works is not required, but enhances the experience. One can see changes of perspective between the first two books and the third one, for example.
And yes, while not ending on a cliff-hanger, it does leave the main characters, and overall galactic situation, a lot of room for further exploration.
