I was sorely disappointed.
Any time spent reading Eldest is time better spent doing almost anything else. The flaws in it are characterized by the fact that it was written by a teenage boy. The writing, for example, in additional to being horrid, puts on tremendous airs [like teenage boys, often]; the text is littered with questionable usages of large, obscure words. The passages in which Paolini tries to give his book some deeper meaning are painful to read, because of the irrelevance and, frankly, the stupidity of the moral issues he tries to address; it is clear that some passages were inserted solely for the purpose of trying to make the book deep (unsuccessfully). As people have said, every character, every situation, and every aspect of the book are copied inexpertly from existing, exponentially better works of fantasy/science fiction. His acknowledgements at the end were irritatingly insolent, with the author thanking everyone he knew and who helped him publish his book, even thanking his characters, and specifically neglecting to acknowledge all of the plot twists, characters, settings, and other ideas, blatantly stolen from more experienced fantasy authors. Everything the author tries to imitate is seen in Eragon in despicable, half-hearted shadow. The languages Paolini creates are clearly a gimmick to amuse Tolkein fans, not created out of a genuine love of linguistics as were those of the latter master author.
At times the plot was action-packed enough to keep one engrossed in reading, but that was just frustrating to me, since it obligated me to keep reading this awful book in order to find out what happened. Looking back on it, however, all of the characters were so bland and distant that its hard for me to believe that I actually cared what happened to them.
Still, I would not even recommend the book to people who would only care about the plot. The plot of the book was not worth the time spent reading 500 pages. The storyline had a consistent, irritating pattern: the heroes would have a problem, they would spend a while trying to come up with a solution, eventually some sort of solution would suddenly appear out of nowhere, the characters would travel for a while until they met another problem and the same thing happened. Despite this annoying suddenness of the solutions, the problems were equally annoyingly foreshadowed, making half the plot boringly predictable, while the other half was confusingly random. Sometimes it seemed like maybe the story had made more sense when it was in the authors head. At risk of appearing harsh, I say, the authors head is probably where this story should have stayed, until he matured in writing and otherwise.