Broken Base: Ed Speleers's performance divides a lot of fans. Some felt he was miscast both for his looks (Eragon of the book being dark haired and brown eyed) and for the Narm in some scenes. Others felt he gave a good performance with what he was given, and in fact, he was the only other cast member to get critical praise besides Jeremy Irons. Notably, despite the film's tepid reception, he was still nominated for a Saturn Award — and though he hasn't had any major film roles since, he's had quite the successful career in television.
Cliché Storm: The Inheritance Cycle was already strongly criticized for the unoriginality of its story, setting, and characters, and the plot of the first book in particular has often been accused of being very derivative of A New Hope, so it was inevitable that the film adaptation would receive similar criticism. However, since the film either removed or severely downplayed the more memorable elements of the books while adding nothing new to make the story stand out, it is widely considered even more unoriginal than its source material. However, it is more creative in some superficial decisions, like the zombie ninjas and the smoke dragons, and even makes a conscious effort to tone down some of the more blatant Tolkien similitudes, such as by portraying the Urgals as feral humans when the book Urgals are pretty much just orcs by a different name.
As in the books, Murtagh. Even fans who disliked the film overall rather enjoyed Garrett Hedlund's performance, and Murtagh is often cited as one of the highlights of the film.
Harsher in Hindsight: Murtagh and Hrothgar sharing a smile at the end of the battle becomes this when you remember that Murtagh killed Hrothgar in Eldest, book 2 of the Inheritance Cycle.
Hilarious in Hindsight: Some of the back covers for the movie describe it as the first film in "the InheritanceTrilogy". During the writing of the third book, Christopher Paolini decided the story was too complex for one book and so split the story between two books, making it a four-book series.
Narm: King Galbatorix's line "I suffer without my stone. DO NOT. PROLONG. MY SUFFERING." It is obviously meant to sound dramatic and threatening, but the wooden delivery and awkward wording make it unintentionally hilarious.
Platonic Writing, Romantic Reading: Despite the attempt to portray Arya and Eragon as Implied Love Interests, as noted below, they don't seem to make much of a connection. He has more chemistry and meaningful interactions with Murtagh, who at the very least becomes Fire-Forged Friends with him. This gets pretty awkward for anyone who has read the books, given that it's revealed Eragon and Murtagh are half-brothers.
Presumed Flop: The film is often mentioned as if it were a gigantic Box Office Bomb. In reality, it was a domestic failure but performed adequately with the help of the international box office, making $250 million worldwide off a $100 million budget. The director even said Fox were "moderately happy" with the worldwide profits. However it was panned critically and received a great deal of backlash from fans of the books, halting plans for a sequel.
Sienna Guillory's casting as Arya raised some eyebrows, mostly because she looks absolutely nothing like the character in the books (the latter is said to have green eyes, black hair and dresses in black leather, while her movie version is a blue-eyed redhead clad mostly in white or lighter colors). Some of these things could, in theory have been changed, but across the board it's fairly obvious that holding to the appearances of the book characters was considered unimportant. Guillory's performance isn't generally one of the things most criticised in the film, but there are still complains about the lack of physical resemblance as well as the Adaptation Personality Change. Interestingly enough, she portrayed Jill Valentine in Resident Evil: Apocalypse as an Aloof Dark-Haired Girl, so she would have been certainly capable of playing Arya more canon accurate.
John Malkovich as the evil overlord in a fantasy epic. Not only does he provide the majority of the film's Narm in his short screen time, but there's no reason for him to even be in the film. Galbatorix is an off page character in the books, not appearing until the fourth. With Durza playing the film's antagonist, it's not as though they needed to do more than have him as The Ghost.
Murtagh's actor would later go on to become the far more recognizable Sam Flynn.
So Okay, It's Average: The story might not be very engaging, but at worst, it's just bland and inoffensive, meaning most viewers can at least take some enjoyment in the Scenery Porn and the weird-but-great special effects, especially those who haven't read the book and so can approach it with a fresh pair of eyes.
Strangled by the Red String: Arya is Promoted to Love Interest - although to the film's credit, it's merely the start and hint of a romance. Except she and Eragon share very few scenes together, and their talk before the battle is in fact their first full conversation alone. And their flirting at the end is only their second. At no point does there seem to be an attraction that forms beyond Eragon thinking she's pretty.
Tear Jerker: The scene where Saphira lets a dying Brom fly with her so that he can truly be a Dragon Rider one last time is, despite the film's mixed reception, genuinely moving.
They Changed It, Now It Sucks!: Largely the reason it's disliked by many fans. In fairness, there are numerous changes which do things like ruining emotional connections (like having Saphira instantly grow up and name herself rather than growing over time and being named after Brom's Dragon) or causing issues with future book plots (like having the Ra'zac be tied to Durza and die during the movie). However the major issues that do exist can also make complaints about things that are ultimately unimportant (like Saphira having feathered wings instead of leathery) come across this way.
Ed Speleers as the title character is obviously trying to make a good impression in his first major acting role, but his stilted delivery combined with a poor script makes for some unintentionally comical moments.
Jeremy Irons, one of the biggest stars in the cast, delivers what is widely considered the film's best performance in his role as Brom, despite the questionable script. Unfortunately, given the overall poor quality of the film, all he really accomplishes is making everyone else look even worse in comparison.
A few characters are clearly wearing off-the-shelf blue jeans.
Ajihad is given a receding hairline with long straight black hair that just looks ridiculous. They'd have been better off leaving Djimon Honsou with his regular bald head.
Nasuada likewise has what looks like a Sci-Fi Bob Haircut with a modern fringe. They might've been trying to give her Power Hair but it looks more like a modern bowl cut, which both doesn't fit with the medieval-esque setting and isn't that flattering on the actress.
Non-human character all look more or less human (with the exception of the Ra'zac, who still look more human than their book appearances).
Arya is explicitly an elf in the books, but lacks pointed ears or other such elf features in the film, to the point where some people even wondered if she was meant to be an elf in this adaptation.
Dwarves are no shorter or stouter than humans. Again, someone could be forgiven for believing there are no dwarves in the movie.
Urgals are perhaps the biggest change from the book, where they are grey, horned and generally larger than humans (some of them can grow up to nine feet tall). In contrast in the movie they are entirely human looking barbarians, differentiated only by their face paint and clothing.
YMMV for the Eragon video game
Badass Decay: Brom sucks in this. He gets beaten up and dragged off by a wolf.
Bizarro Episode: Hadarac Desert. You never go back and there is no explanation for destroying the Urgal camps. On the other hand, you do meet Murtagh there.
