I've been reading through this for the past few days, and I'm very impressed. I'm not quite through reading it, but everything I've seen so far gives me high hopes.
StarJammer is a mix of both magic and sci-fi, and blends these two very well. Races are interesting and feel fresh and even the traditional Pathfinder races have been given a new coat of paint.
The artwork throughout is gorgeous (though the art for Abiarazi confuses me. If they are shapechanging blobs, it should either be a blob or look like one of the other races. The art for it looks great, but it seems an odd choice). I also like how how humans are sort of the "bad guys" of the galaxy's fantasy races, for their consuming nature (tyranid humans anyone?)
The new feats are great though there's only 18 of them. They are all focused on "space" (combat, living in it and so on), so they fit well into the nature o a sci-fi setting.
The equipment sections starts by explaing the currency of space-based civilizaion and paper currency. But then reverts to calling it GP in the text of the equipment. I suppose it's to keep compatability with Pathfinder, so it's a minor quibble. (Also, I need laser guns. Lots of armor but no weapons? Seems a bit odd)
1st level characters get a free vessel! YES! Time to travel the stars in... Well, not exactly style, but my characters will be travelling the stars from the beginning.
Hazards and planets are well-described and include all the things you'd expect (I'm a particular fan of the Dread and Lightning worlds, and I can just imagine the look in the eyes of players when they find a Mithral world). The sample worlds are cool too, I especially lije Iste Golan and look forward to stranding PCs in a "military training exercise" of the Infinite Legion.
The deity section seems heavily Lovecraftian to me, and only contains 2 good gods (one of each of good, neutral and evil are detailed with a table showing a few more).
Just starting the Travel section now, but I'm very happy with this release, even if had no more than what I've read so far. :)
[5 of 5 Stars!]