Eragon received generally mixed reviews and was criticized for its derivative nature. Liz Rosenberg of The New York Times Book Review criticized Eragon for having "clichéd descriptions", "B-movie dialogue", "awkward and gangly" prose." However, she concluded the review by noting that "for all its flaws, it is an authentic work of great talent". School Library Journal wrote that in Eragon "sometimes the magic solutions are just too convenient for getting out of difficult situations". Common Sense Media called Eragon's dialogue "long-winded" and "clichéd", with a plot "straight out of Star Wars by way of The Lord of the Rings, with bits of other great fantasies thrown in here and there." The website did concede that the book is a notable achievement for such a young author, and that it would be "appreciated" by younger fans.
Favorable reviews of Eragon often focused on the book's characters and plot. IGN's Matt Casamassina called the book "entertaining", and added that "Paolini demonstrates that he understands how to hold the reader's eyes and this is what ultimately separates Eragon from countless other me-too fantasy novels." Chris Lawrence of About.com thought the book had all the "traditional ingredients" that make a fantasy novel "enjoyable". The book was a "fun read" for him because it is "quick and exciting" and "packed" with action and magic. Lawrence concluded his review by giving the book a rating of 3.8/5, commenting that "the characters are interesting, the plot is engrossing, and you know the good guy will win in the end."
Eragon was the third best-selling children's hardback book of 2003, and the second best-selling children's paperback of 2005. It placed on the New York Times Children's Books Best Seller list for 121 weeks. In 2006, the novel was awarded with a Nene Award by the children of Hawaii. It won the Rebecca Caudill Young Reader's Book Award and the Young Reader's Choice Award the same year.