There is a train of thought that something created in one medium should translate pretty seamlessly into another, vastly different one, and disappointment ensues when things don't quite go as anticipated. It's happened throughout history, ever since books were adapted for a cinematic audience, and with games now a major entertainment business it gives rise to more crossover opportunities; in the case of Eragon, for example, there is a series of books, a soon-to-be released film, and the game, which is presumably why you are here. So already there is a fan base 'out there', but of course that poses a different problem: is the primary audience those that want a fun fantasy hack-and-slash game or a companion piece to the books/film?
Let's deal with the latter part of that question first. Our journey starts with the titular young farmhand as he hunts his lunch in the forest. Meanwhile, a mystical girl clutching a glowing egg is being chased by an even more mystical fellow, who surrounds her and demands the egg. She refuses, throws the egg into the forest, and is taken prisoner. You find it, learn it's an egg and disappear. Soon it hatches and a dragon emerges, which Eragon names Saphira, after the colour of her hide. During the elapsed time (no indication is given as to how long, exactly), the evil king Galvatorix wants Saphira and you dead, and sends his minions (led by Durza) to locate you. Quite why this means you need to rid the land of some evil-dudes I'm not sure, but off you go on your travels where you will plod through 16 levels with some companions and your dragon. At least, that's what I think happens; I don't really know.
You see, having neither read the books nor seen the yet-to-be-released film, I know nothing of the story, and yet the game does nothing to help me understand. Indeed, it almost expects you to know everything there is to know about Eragon, Saphira (the dragon), Durza (the evil dude) and so on. And, based on the information my eldest son tells me (who has read the first two books), various events don't happen or are out-of-synch, and fairly important characters are left out completely or, where they do appear, are neglected or thrust upon you with little explanation. At any rate, I felt I learnt little from the brief cutscenes and narration that interspersed the levels. Suffice to say, it's unlikely you'll keep playing to find out what happens at the end.
So, as a supplementary piece to the books or film it fails, rather expecting too much insider knowledge of the player. So what of the actual game, then? Straight off the bat, let's get the most probable comparison out of the way: this is not a Lord of the Rings rip-off: Eragon cannot come even close to matching the presentation values, graphical splendour (relatively speaking) or depth of gameplay seen in those titles, and in a way is more in keeping with something like Drakengard's mix of on-foot/in-air gameplay.
Split into two sections, the majority of the game's levels grant you control of Eragon, with a companion that can be either AI or friend-controlled. You're tasked with killing lots of humans, goblins, troll-like beasts and other fantasy creatures until you reach the abrupt end of each level. You'll do so from the genre-standard third-person perspective, and you'll have access to the now-requisite quick attack, a slower, stronger attack and the surprisingly-useful grapples, and these can be mixed-and-matched to create various combos. Sadly, what you start with is all you will ever have when it comes to combat moves; a somewhat foolish developer choice means that you cannot upgrade your skills at all during the game, so there is never any payoff to reward the endless killing.
In addition to the meagre library of physical attacks in your arsenal you'll also acquire some rudimentary magic abilities (which are thoroughly underwhelming) and be able to make use of the bow that magically floats on your back and fires arrows that appear from nowhere. At various sign-posted points you'll use your telekinetic ability to interact with the environmental hotspots to create bridges from planks, or pull stones from the ground to solve the basic puzzles that await you. Rarely has a game continued to hold your hand throughout, and the contrived nature of it all, combined with the linear level structure, gives rise to the impression that the developers felt they had to shoehorn magic in somewhere, but didn't really know how.
As you'll probably know by now, the other star of the show is Saphira. In addition to having some of her own levels she'll occasionally make an appearance during Eragon's adventures, although she is only allowed to help in a few situations. Her own dedicated sections are on-rails affairs - think Panzer Dragoon Orta. They are also uniformly diabolical, suffering from some of the worst controls I have ever had to endure. You see, you have no control over the route taken through the levels, but you can move Saphira around the screen without deviating from the prescribed course; this is coupled with a floaty camera that thinks nothing of feinting to go in one direction before swiftly moving the opposite way (and ensuring you crash into the scenery in the process). These levels are frustrating and so beyond not being fun it's staggering.
Of course, much like her bipedal-friend, Saphira has special attacks too, and you'll have a tail whip (inaccurate and aiming at ground troops will cause you to hit the floor), flame breath (same problem when aiming), and quite possibly the most pointless ability ever: a speed burst. It is rendered worthless due to the small, tight, obstacle-crammed looping nature of the levels, and as a consequence you never have any need to use it. If you do, all that happens is some screen blur and you crashing into something. In a game full of strange design decisions, this takes the biscuit.
It is this kind of approach that permeates throughout Eragon. Saphira's levels feel unfinished and clearly lack purpose (other than to get her into the game to please the suits/fans), and Eragon's levels are terminally dull and very much gaming-by-numbers, with nothing to excite or astound. It looks competent (but still suffers from slowdown, clipping and dubious collision-detection problems), the music is repetitive (but reducing the volume reduces the sound effects also), and the presentation is shonky at best. If anything, the biggest criticism that can be levelled against it is that it feels as though the developers really didn't know LotR and games of that ilk exist; it takes a huge backward step for the genre, and doesn't offset this through appetising visuals or sublime gameplay. If the film were in any way comparable you'd expect to see the strings holding a cardboard Saphira up in the flying scenes, with a miniature doll sitting atop it. Not every game has to revolutionise things; evolving is good enough, but Eragon does neither.
Casting judgement on Eragon is not a difficult act. Cynicism aside (of course its purpose is to cash-in on the books/film), there is nothing in Eragon to warrant playing it, unless you're a hardcore achievement-point chaser or must have everything Eragon-related. When you consider that the 360 already has other similar titles - think Ninety-Nine Nights, Dynasty Warriors, hell, even Kameo - all of which are better games (yes, all of them!), you just don't need this. Based on the on-foot levels alone, this would be poor. But when you add in the frustration and pointlessness of the Saphira levels, it just gets worse. Lovers of the book and/or film may find slightly more to enjoy here than out-and-out gamers, but they'll probably be more disappointed given the higher expectations they'll have. Either way, it's a pretty awful attempt to successfully cross the media-divide, so hopes will have to be pinned elsewhere.