I could write an entire book on why Inheritance is amazing. But I'll stick to a smaller review.
This is the last book in the Inheritance Cycle. The stakes have never been higher. The evil is so powerful, you can't possible see how Eragon and Saphira can win. They're so outnumbered.
The character development is amazing. Eragon and Saphira mostly, but also the secondary characters.
The DETAILS. The details are amazing. You read it and you can imagine exactly what the scene looks like.
The ending-- well, I won't say anything about that except that it is so good. it's not your typical book ending, which is why I like it.