I read Worlds at the same time as Orson Scott Card's The Lost Gate. I had worried about Card's possible inclusion of politics, but it didn't happen. Haldeman's book, on the other hand, is all about politics. The Lost Gate was a quicker read, and more fun.
My main acquaintance with Joe Haldeman's writing is via his Forever series (which was good), but I've read a good handful of his other books. In some recent books, he seems to be trying to recapture the spirit of Heinlein's early days. He's done moderately well with the politics, less well with the characters.
This particular book reminded me heavily of Heinlein's Podkayne of Mars, and of Haldeman's own Marsbound. (Though really that should be the other way around - Worlds was written before Marsbound.) In any case, plucky, talented young woman taken out her element, meets strong men, presents polemics disguised as introspection, lots of sex all round.
Unfortunately, while the politics is not troubling in itself - and in a book about politics, I allow a lot more leeway - it's also not very interesting. It was too clear that Haldeman had put together a plot based on concepts, and stretched a human interest story around it, disregarding the thin spots. The characters are thin, sometimes inconsistent, and, despite O'Hara's orbital upbringing, traditional to a T (but with more sex). O'Hara, for example, brought up to be casual and comfortable about sex, varies between fearing someone will make a pass, and wishing someone would. It's a rare event that she makes one herself.
Mostly, I just found the book slow going. It wasn't difficult or dense, but it was dull. There's quite lot of travelogue - far more than is needed for Haldeman to comment on funny Earth customs. It eventually began to feel like sitting through a distant cousin's holiday slideshow, with no discreet way to sneak out the door.
All in all, a moderately interesting take on a story I felt I'd read many times before, and in most cases better presented. If you haven't read a lot of Heinlein, Pournelle, or John Barnes, or if you like those guys a lot, you may like this. Otherwise, I don't think there's a lot that's new for you here, and what there is is pretty slow going.
This was an advance copy. Mine was chock-full of OCR typos - dozens of them. I hope they've been cleared up in the final version. If not, you'll have a very aggravating reading experience.