Taken from Mark Siegal’s LJ – a lovely, wonderful, essay written by Elizabeth Bear on setting and voice.
In any case, successfully written narrative, whether it’s exposition, setting, action–ideally, a mix of all of the above, as necessary, to the point where it becomes invisibly multifunctional) should engage the reader both intellectually and emotionally. It’s not easy to do, of course, and it requires both reasonably good prose skills and an organic control of one’s storytelling… and an engaging voice really doesn’t hurt either… but well-managed, it can help create that elusive sense of place that keeps the Viking princess from coming across as a Valley girl.