For most multi-platform releases, you can usually point to a particular version of the game as the "best". For Eragon, it's unquestionably the 360 version of the title, which contains a significant amount of extra material and graphics that are significantly nicer than the Xbox version. This being said, it's hard to play Eragon without realizing that this was probably in development for several years as a title primarily for the Xbox. It uses the older engine StormFront first used in their Lord of the Rings: The Two Towers beat 'em up game, which was primarily for the Xbox and PS2. While Eragon on the 360 certainly looks far too good to be an Xbox title at points, there are also points where it is clearly not making optimal use of the 360. The result is a game that looks more than a bit like Scarface for the 360, and other slightly rushed 360 ports. It can be a little frustrating at points, especially when you get to the dragon flight levels. Since they use a new and totally different engine than the beat 'em up aspects, the graphical quality increases enormously during these segments of the game, and you get a taste of what an Eragon with an engine fully rebuilt for the 360 could've looked like.
Don't let the workmanlike graphics put you off of Eragon, though. This title's gameplay is entirely solid, and actually a very enjoyable spin on the long-since-tired beat 'em up genre. The dragon flight levels not only add challenge and graphical interest, but also help keep the gameplay varied and fresh. There are some repetitive moments in Eragon, particularly on highest difficulty, but they're little more than a scene here, part of a battle there. Otherwise the game plays out a bit like a marvelous 3D storybook, where you travel from puzzle to battle to story event.