I first picked up the Inheritance Cycle books when I was doing a project on books that were written by teens, last fall. While I was impressed that Eragon was written by a 15-year-old, it really wasn't very well written. It was fun to read, and if the story was derivative, well, what can you expect from a teenage fan of fantasy writing their first book? I did read the second book soon after, and found that the writing had gotten better. Brisingr is definitely readable, Paolini's style has improved, and I am still enjoying the story of Eragon and his dragon Saphira.
I was honestly really surprised by some of the turns the plot took in Eldest - I wondered to myself how Paolini was going to solve the quandries he had created. Nothing is really resolved in this book, but the plot definitely moves forward, and I have hope that Paolini will be able to resolve all of the loose ends satisfactorily in the fourth book. My main complaints about this third title are probably the same as my complaints for the second book. It feels as though Paolini is writing the book with a thesaurus at his side, and sometimes he seems to choose a word simply because it is larger and less well-known, not because it fits perfectly in a sentence. Similarly, his use of the dwarven, elvish, and other languages he creates for his world is ponderous at times.
I would recommend this series to any teen who enjoys fantasy, especially dragons. The book does not seem derivative if you have less to compare it to, and it exposes anyone who reads it to the themes of the hero's journey. This book is the least derivative so far - revelations about Eragon's true parentage make it so that he is no longer the son of Darth Vader with sibling he never knew of. We are no longer following as closely to a Star Wars plot-line, although, as mentioned above, it is still a story of the hero's journey, making it extremely recognizable to anyone who is well-read. These books are fun, although they could not be called light reading, and should be given a chance beyond just groaning about how similar they are to every other fantasy out there. They do stand on their own.