Where flight combat games are concerned, I've had my share of heartbreak. For my money, nothing yet quite matches up to
Time Pilot, but that's probably just my nostalgia talking. If I were trying to carry an analogy past the breaking point, I'd say that
TP got right what most games like this get wrong. With
TP, no matter where you went, you could still shoot down enemies and move toward your goal. The navigation was all about fighting rather than exploring. When you were far enough along, you could fight some great boss that came to you (how convenient) and signaled the change to a new level. This went on indefinitely. The flying was easy to learn, so the fighting could be your focus.
Eragon falls into a rut quickly because it doesn't offer much fun gameplay. The missions are too predictable. "On rails" would be another phrase that applies. When you get a shot at multiplayer, it's possible to have more fun, but the overall experience falls short of a good time. The first mission being vanilla is acceptable for training purposes, but the subsequent missions are not much different. There also is no gameplay apart from the flying, which will seem strange to readers who liked the story between the humans as much as the dragon action.
If dragon action is your thing, a case could be made for Eragon as a good game. If you really, really like flight combat games, there might also be a good spin on this. All the typical elements from flying/fighting games can be found, including bombing runs and lots of wheeling about the sky locking on targets. The ground-based enemies don't pose a challenge and don't seem capable of damaging you, unless you just sit in the sky like a big drago-kite. As you play, there are new abilities and skills that Eragon adds to his arsenal and Saphira also gets a few upgrades. This allows you to fight larger enemies or more at once, but it doesn't make the game fun to play. "More of the same" is not a strategy for much of anything except compound interest.