Eldest contains some good character development and (without giving too much away) a pretty exciting battle near the end that makes up for some of the poor writing in other places. Brisingr felt like a waste of time to me, because he totally could've wrapped up the series. Instead the story is dragged out over minutiae while major plot and character elements get ignored. I'll probably read book 4 when it arrives... but only to find out what happens to Murtagh. I've talked to some of my friends about the series and they agree that he's the only one carrying the weight of the story at this point. *shrug*

I haven't read the Westerfeld books. Would you recommend reading only the first 3?