Say what you will, but Eragon can be a compelling story regardless of what you think it ripped off. With that in mind, I give you Edward Speelers...who probably wouldn't know something compelling if it hit him in the face. In fact, I doubt he would even flinch if something hit him in the face. The biggest problem with Eragon is who plays Eragon himself.
There's an innocence-turned-hard required for this role, but Speelers has one facial gesture: solemnity. When he laughs or smiles or cries (tries to, anyway), it is not believable. He is as wooden a leading actor that I have ever seen in a mainstream film. The fact that the story and the movie is carried upon his shoulders is a problem.
The rest of the performances are at least a little better; John Malkovich chews up the scenery like no other, and it works here. Carlyle's Durza is truly a menace, even though his most prominent scenes are often shrouded in special effects.
That is another thing: the special effects. Some are absolutely stunning (Saphira, the journey through the mountains), yet some are so shoddy that they make you roll your eyes. It's almost as if the filmmakers spent far too much time on Saphira and the accompanying flying scenes to be bothered to put much effort into the rest of them.
In summary, it can be thrilling and visually stimulating at times, but Speelers falls so flat that it ultimately is forgettable. It's a shame that this is a such a mediocre film.