It uses an approach similar to Wolverine and the X-Men by drawing from every part of continuity imaginable. However, while the recent X-Men cartoon did so in a contradictory and haphazard fashion ( which, to be fair, describes its source material well ), the Avengers cartoon gives us what could be the definitive version of the team.
The micro-episodes especially made a convincing set-up that gave the characters a sense of importance. We were shown-- not told, shown-- that all these guys are the best and brightest, in spite of their checkered pasts. And it made their convergence as a team believable, even for a Marvel world.
Plus, as the world's first and foremost SteveBlumologist, the WW2 flashbacks met my approval. Not only did the ubiquitous tough guy VA do a good job as the Red Skull, but he reprised one of his most legendary roles as one Private James Howlett...