There'll be some SPOILERS below. You have been warned.
The Curse of Chalion is a stand-alone fantasy novel, set in a new world, and thus represents a bit of a departure for Bujold (whose other fantasy novel I haven't read). It starts off in a much different manner than the typical Vorkosigan book, too, with a beaten and seemingly broken former soldier, Lupe dy Cazaril, limping his way back to the castle where he had served as a page years before. He's hoping for nothing more than a menial job, but what he gets is a much more meaningful position, as the tutor and secretary to the princess (called "royesse" here) Iselle, second in line for the throne of Chalion (currently held by her older half-brother, with her younger brother in line ahead of her).
The plot takes a while to get going (the titular curse isn't revealed until about halfway through), but moves smoothly along its course. Cazaril recovers his wits and self-confidence, just in time to be able to deal with the powerful noble enemies who had betrayed him to a life as a galley slave some years earlier. Will he save his royal charge from their machinations? Will he gain revenge for himself? Will he be able to lift the curse on the royal house of Chalion (once he learns about it)? Of course he will...
The real focus of the book, and its greatest strength, is the world Bujold has created, and specifically its theology. Chalion is ruled by five gods, four associated with the seasons (the Father of Winter, the Mother of Summer, the Son of Autumn, and the Daughter of Spring), and one god who governs events out of time (the Bastard). These gods are constrained to act only through human agents-- in particular, through those individuals ("saints") who have become desperate enough to surrender their will totally to one god or another. The one semi-exception to the rule is the death magic of the Bastard-- a person can call upon the Bastard to kill an enemny, at the cost of the summoner's own life. It's a nicely balanced Ultimate Weapon of sorts-- it allows the killing of an arbitrarily powerful enemy, but the price is high enough to prevent capricious use.
The theology is well worked out, and there's some nice material on the mentality of those who become saints, and what it's like to be completely subject to the whims of the gods. The tangled politics of the capital are also nicely drawn, as are the effects of the curse, and the way it attacks the royal family and its supporters. The prose, as always for Bujold, is eminently (almost compulsively) readable, save for a couple of chunks o' exposition which verge on the "As You Know, Bob."
There are a couple of fairly serious problems with the book, though. At the start, Cazaril is nicely distinct, both from other characters in the book, and from other characters that Bujold has written. As the book progresses, though, and he regains his confidence and competence, he starts to sound more and more, well, Bujoldian. The same disease afflicts his charges as well-- by the end of the book, conversations between Cazaril, Iselle, and Cazaril's love interest Betriz sound like a reunion of distant Vorkosigan cousins.
More importantly, the plot, which has glided along smoothly for most of the book, sort of comes off the rails at the end, turning on an incredible coincidence (the discovery that Iselle's intended husband was the slave Cazaril acted to save a year or two earlier), some downright legalistic prophetical hair-splitting (one of Cazaril's deaths being retroactively deemed on behalf of the royal family), and a rather confusing explanation of the origin and undoing of the curse. Cazaril's survival also felt like a bit of a cheat, but it's par for the genre, so I can't complain too much about it.
All in all, this was a fun read. It kept me up late reading, which says something. The dissatisfying ending keeps it from being a really excellent book, though. Of course, the step down to "very good" isn't that big...