Don't waste your time.
In a nutshell, this book is turgid, bloated, and unrewarding.
The protagonist, Eragon, is the textbook definition of psychopathic, murdering innocent coerced soldiers without any regret. He seems to delight in doing so.
Roran is unbelievable and boring. He kills over two hundred people with a hammer and then stands on the pile of bodies.
Nasuada seems to think that the best way to convince her enemies how strong she is would be self-harm. Huh.
The plot does not warrant the page count and could have been written in under 70 pages, not 750. Don't believe me? Fact: there are only 5 plot points. The decision for a fourth book is only to get more money. Paolini is obviously worried that when Inheritance is finished, no publisher will want to touch his books. He should be worried. Brisingr doesn't even look as if it's been edited.
Christopher Paolini cannot write. He does not know how to use a simile. The purpose of a simile is to compare two things, describing the former of the two, something unfamiliar to the reader, by comparing it with something the reader is familiar with. The are not for comparing two things that both need separate similes. They are not for boosting word counts.
I won't go on any more, except to mention the plagiarism, for which there is documented proof, and the language Paolini claims to have invented (It's actually Old Norse, and he butchered it.) Paolini is not a Tolkien. Prof. Tolkien was a linguist. Paolini isn't. End of Story. (I wish.)
This title contains:
Violence & scariness
Drinking, Drugs & Smoking