Taking place less than a year after the end of Eragon, Eldest switches between Eragon and his cousin Roran's POV as they adventure forth, battle, and, ultimately, try to defeat the evil King Galbatorix. Paolini's description of Ellesmera was breathtaking and fascinating; as a kid, I loved this magical elf world and, as I grew up, I loved the fact that while Eragon is portrayed a little too Mary Sue-like, (view spoiler)[Arya rejects him - he doesn't get the girl! (hide spoiler)] 
 The Inheritance Cycle was one of the first fantasy series I ever read growing up, so I idolized the series a little more than I should have - now that I'm older, the use of cliches and tropes is overwhelming. Paolini struck some blows at religion in Ellesmera, and that was, I think, more interesting and developed than the cliche he'd been following up until that point. Eragon also seemed to have aged a lot since the end of the first novel - even though it takes place less than a year later, he seemed to have aged unrealistically a few years. 
 While I liked both Eragon and Eldest well enough as a kid, I never did finish the series; now, I think I've grown out of it and it will probably remain that way.