I'm on the fence about whether SWSE's comprehensiveness counts as a strength or a weakness. On the one hand, it's a one-volume Star Wars rpg. The core book has everything you need. Not just heroes, but creatures, droids, vehicles, setting, campaign suggestions, and GMing advice. It's a hell of a bargain, and you'd be hard pressed to find a more thorough book at 240 pages.
And yet, the downside to that thoroughness is that a lot of the GM stuff feels half-baked. The setting chapter is 10 pages, with 19 planets getting about a half-page each (and these are SWSE's oddly-sized square pages, at that). It's not really enough. The locations get a quick outline at a very high level of abstraction. Enough to start the work of world-building, but literally only the first step.
The creatures are even worse. The Star Wars universe has a bunch of wild and improbable space monsters, but the book just sort of throws up its hands and gives you a barely-functional class system with which to build them yourself.
There are examples of how it will work, covering some of the series' most iconic creatures, but if you used the Rancor's stats as written, you'd be setting your party up for one of the worst fights not only in d20, but possibly in all of D&D-family gaming. It's basically D&D Basic-level monster technology, but with none of that system's virtues of simplicity. Luckily, D&D 4e monsters are fairly easy to adapt to SWSE, so the universe of the game need not be barren, but using the core only, you'd have to seriously consider using humanoid enemies exclusively.
However, I am not sure I really need to ding SWSE for this. We all know what Star Wars is, and what a Star Wars story should look like. Because of that, the book's paucity of setting information isn't really that much of a problem. I'm not sure what the overlap is between "people who want to play a Star Wars rpg" and "people who need the Rebellion against the Galactic Empire meticulously explained to them," but I'm certain it isn't large.
In the end, my verdict on this game is colored by my experiences with it. I ran a SWSE game that was basically core-only (the supplements were available to use, but I'm the only person who ever read them) and it ranks as one of my better rpg experiences. The players all had a lot of fun, and my baseline familiarity with the material let me do a lot of worldbuilding without consulting the books. So, for the sake of notalgia, if nothing else (certainly, it's improbable that a lot of new players are going to swallow the $70 price tag a used book fetches on Amazon) I have to give this a thumbs up.
(Enough that I'm looking forward to running a new game with it, at least).
UKSS Contribution: I think this is a milestone. The first primarily sci-fi game to go into UKSS (Heroes Unlimited had sci-fi elements, but superpowers are easy to reskin as magic). I'm excited to see what reading these books is going to do to UKSS' genre.
Still, I had to work a little with this one, so as to avoid borrowing anything too iconic to the movies. I wound up correlating something from the Species chapter with a blurb about one of the planets in the setting chapter - Ithorian floating eco-cities.
These Ithorians are weird snail-creatures that love environmentalism and specialize in rehabilitating ecologically devastated worlds. They are so committed to ecology that on their home world, they don't even live on the ground anymore. Their cities fly above the earth, presumably using some sort of low-emissions sci-fi-type engines.
That little detail might be cool for a druid-inspired faction in UKSS.