OK so I have read all the way through the first three Rocketship Empires books and I am impressed. The core book is awesome, just overflowing with fun gameplay ideas and cool setting. The Gunslinger Betty is one of the most in depth, single subject sourcebooks I have ever read. The whole thing is on one plane and he even gives diagrams and pictures from a real B-25. With this much information players can make meaningful repair decisions instead of just a bland roll. In Fury Triumphant does a good job of laying out the Spanish Civil War in space and really sets things up for the upcoming adventure module.
Even as I finished reading those three the next book, Starship Compendium, dropped. I tell you the man is a machine. I will be reading this one this week.
There is a little bit of strangeness with the setting though. It is obvious that it is meant to be pulp action, fast and loose. However the ships cry out for a high level of fidelity in the rules system. A lot of time has been spent to offer many, many awesome ship options. A rule system like Savage Worlds would be perfect for everything outside of the ships. The problem is that Savage Worlds, and similar systems, does not offer the granularity to distinguish between all the different ship options. Also skill consolidation in these kinds of systems means that you will have blanket repair and piloting rolls, when the setting supports many more choices.
Obviously this is not a deal killer, people who use Savage Worlds probably are not looking for tiny differences in ships so they can just gloss it over. The ship creation setup in the books will make it mesh nicely with GURPS, Hero System etc. The problem is that the out of ship parts of the setting do not go into this level of detail (yet). It is more just an annoyance with the continuity of level of detail than an actual complaint.
There is some spelling and layout ugliness but it is not too bad, and I know from reading the forums that he is working hard to eliminate this from future books. One of my main complaints is organizational. The books read great. As you read through the setting he fills you in on bits and pieces of how things work and then jumps back to the setting. While this is a fun way to read it, it will be hell when I need to find something. Information on related subjects really need to be together. Since the book is systemless I can understand the desire to make it a smooth read, but at least there should be a solid index.
These are nitpicks, as he develops his style more I am sure that all of this will be smoothed out. These books are all very, very good. The setting looks like a blast and I cannot wait to play a game in it.