Planetary Generation (Why I bought this, I have not heard of Clement Sector other than in Passing) It seems to be an interesting mix of influences from (likely) Classic Traveller book 6 Scouts, Grand Survey's Details of Atmospheres, and a serious focus on The Luminosity of Parent Stars, but looser than something like GURPS Space 4th Edition, or Traveller:Interstellar Wars...but with a prevalence for Clement Sector Specific Details, most lesser worlds of a system will be (If inhabited) captive govt, research stations, military bases, with the occassional High Law prison or independant world.
I think I can say if you like the idea of bold exploration by Scouts / Colonists / Corpporations going into a mostly unihabited Area of space to break rocks, mine moons, sets up colonies, i.e. you have embraced the Clement Sector's Setup / Paradigms, this is the book for you. If you are seeking a more open ended kind of Science Fiction Basic Principles, roll it out and see what you get, GURPS Space 4th is the more detailed, not so setting specific.
I can see a lot of work went into this product. Again, if you are a fan of Celement Sector, this is a great resource, very detailed. If you came here for system Generation, and you have not been a Traveller fan since the old days, and do not have access to the system generation stuff from older systems, this does an okay job, given the setting parameters.
I much respect the amount of work that went into this product. 4 Stars.