First the good stuff: We start off with a couple of new races, info on the standard races, and then some racial archetypes. This is followed by some archetypes for classes, and faction information for new factions. We have some new skills and feats, as well as new spells and equipment. All of this takes up some 90-odd pages.
After this, we have more than a 100 pages of GREAT stuff. The stuff we all want - Space! Or rather, the Void, as it is called. First there is the hazards, with random encounter tables for things like meteor showers, radiation belts and wormholes (but not limited to just these!). This is followed by information regarding different types of planets you might encounter, and the environmental hazards that might accompany them. Enough information for you to create hundreds of different worlds your group might visit. There are also a number of pre-built worlds, complete with adventure hooks for each world. And then even more info, for example trade goods from different worlds.
And then we come to the reason we all want this product - the rules for traveling the Void. Rules to build your own ships. What (and number of) crew you will need, complete with bonuses if your crew is specially skilled in their position. For example, a Tactical Officer can give you bonuses on attack rolls against enemy vessels, as well as bonuses in combat against enemy crew who may have boarded your vessel. And if you don't have enough PC's to crew your ship? Well, you can then hire NPC's, or your DM might allow you to buy droids that can fulfill certain tasks.
On the ships themselves, you can have anything from a Ultralight vessel, usable by and intended for a single character, all the way to Superheavy vessels which are the flagships of space-navy fleets, and which can have entire invading armies on board! There are pre-built vessels, but (more importantly) there is also rules for building your very own vessel! And all of this is only starting to touch all of the information in the book!
Pros: It is Spelljammer for Pathfinder. Need I say more?
Cons: This book references other Paizo material. However, the material referenced is available on D20PFSRD.COM