The series also manages to cover several major events in comics history pretty well, including "Secret Invasion", the Kree/Skrull War and the "Winter Soldier" arc of Captain America. Classic villains like The Masters of Evil and the Serpent Society are recurring antagonists, which is actually really fun to see, especially when they have to team up with some of the heroes in the second season episode "Assault on 42", probably one of the best in the series. Of all the guest characters, it's actually Spider-man and Luke Cage that stand out the most, even more so that Rocket and Groot, with Spidey falling nicely into his sempai/kohai relationship with Cap and Luke just having some of the best lines and constantly billing Tony Stark for services rendered.
AEMH is not as good as it once was, now that we have so many great MCU entries, but it is worth watching if you feel like something a bit closer to the comics without getting bogged down in continuity. The characters work, most of the writing is solid and a handful of episodes are really good. It would also work as a primer on the broad strokes of the Marvel 616 Universe if you or someone you know is keen on wanting to learn more, especially with some of the more obtuse points like Yellowjacket, the Supreme Intelligence and Red Hulk. It never reaches the same heights as Justice League Unlimited, but AEMH is still the best animated version of this team to get a full series of its own. Avengers Assemble!