What a great series of novels! One of my favorite high fantasy series, actually (and the first I ever read on my new nook!). Three things:
1) Finally an author that takes emotional relationships seriously, and doesn't just use "true love" as a plot point or an exploitive device. "Love is about trust" is the main message, and I find that to be a useful idea in real life, as well.
2) Extremely interesting magic system (again, one of the best I've read) that all comes from simple, clean first principles and then allows for unexpected combinations.
3) He is consistently reversing and then re-reversing your expectations, slowly allowing you to discover more and more information about the world, each bit changing your view just a bit. The ultimate in unreliable narration, but without betraying the readers' trust.
Also, it's a hilarious riff on the Wheel of Time series, the series that he eventually took control of.