It is out of date. The Starships of the Galaxy worked with the original rules for Star Wars RPG d20. Since the revised rule book came out, many of the things in this book are no longer valid, just as the range increment or even the Starship record sheet. But is it still worth it? well that's for you to decide.
I write many different types of campaigns, and one of the types i write cater towards those people who put a lot of points in Pilot and Astrogate skills, as well as those who ventured into the Ace Pilot or Jedi Ace prestige classes. With this book i have managed to come up with so many varieties of craft and made so much available to my heroes. This book gives you guidelines for creating small craft (starfighters and transports) capital class (Star Destroyers, Frigates) and space stations (Executor, Hosk). It comes in very handy when for a reference on how to modify a craft. I use it a lot when writing these types of campaigns to try and provide a craft for the heroes on a budget. It list out many things about creation of starcraft that i wouldn't be able to write these modules without it.
It lacks in many departments as well, partly due to the outdated rules it was based off of. First of all, the combat system for space combat and airspeeder combat has changed dramatically, from abstract to a grid. So range increment is no longer needed and now the Speed needs to signify how many squares the ship can move. Since Ramming is the fastest Ion engine in this book, you're left wondering why a Ramming-class ion engine in the X-wing only moves 10 squares while the Ramming-class ion engine in the Millennium Falcon moves 12 squares. (RCR p 277 & 230). There is no clarification for this. As well many craft have a different atmospheric speed, this book doesn't even mention that. Another smaller problem are the prestige clases, they're outdated and you have to get the official Errata from WoTC.
Final verdict? I use it a lot when writing. I use it for the creation purposes of starships, capital to small, and even installations. I've already created my own starship record sheet. See if you can find this book for a cheaper price... becuase right now it really isn't worth what many places are asking for it...