I checked out the official website of Eragon: www.alagaesia.com. I read about Christopher Paolini. It's no wonder I think his prose will (and should) still develop. He's not really a writer. What I mean is: He's got this wonderful story. He's got the plot of the whole Inheritance Trilogy mapped out. But the actual writing is different from inventing a wonderful story. Paolini himself admitted that editing Eragon took two years and that he's still learning the craft/skills of creative writing. (He also admitted that some of the editing was necessary because of some grammar rules he wasn't really aware of.) He's learning by doing.
Again, please don't get me wrong. I am enjoying reading Eragon! =) (I am only halfway through the book because I have a lot of reading to do for my MA class.)