Just saw the last four episodes. Really enjoyed all of them! New Avengers was a fun showcase of some of the other heroes while also bringing Kang back into the picture (Loved the new team taking the place of the old team in the opening and Wolverine causing extinction himself.), Operation Galactic Storm and Live Kree or Die were a fantastic pair of episodes with some great character moments (Yellowjacket's and Vision's, especially. It's about time!) and Avengers Assemble was a great finale that ended things with a bang. Sure, it definitely could've benefited from being a two-parter, but as a whole, I'm overall satisfied with how it ended: Just a straight up war between Galactus and the Avengers leading an army of Earth's heroes. That's one HECK of a send-off.
As a whole, I very much enjoyed Season 2. (Even some of the weaker points.) I wish they could've finished the Surtur plot, but hey, what are ya gonna do? Hopefully, Mr. Yost will address it in the spin-off comic series. If this truly is the end, then I'd say that it had a good run. 52 episodes is nothing to sneeze at compared to some other Marvel shows and It told a good number of great stories in the long run. As for what awaits in the future with Avengers Assemble, I'm going to stay positive and hope for the best. Farewell, Avengers: Earth's Mightiest Heroes. You will be missed and remembered as one of the greatest Marvel animated shows of all time.