(very little or no spoilers) This show has been solitary in a niche that has been left alone in the entertainment industry for a while, that niche being a show that has great appeal to almost very demographic, ESPECIALLY in the competitive superhero industry. While you may just think of this show as another kids show that gives some children a fun 30 minutes of entertainment, Earth's Mightiest Heroes shines as, arguably, the most comic accurate superhero adaptation (including films) to date amongst the show's followers.
This show is PERFECT for people who want accurate info on the Marvel Universe, and is a great introduction to more extensive characters and more precise origins, such as Hank Pym creating Ultron and the character of Kang the Conqueror. Voice acting is superb, animation greatly supports the already great action that is adrenaline-pumping, yet not too violent for a younger audience (if you're worried of such a situation). As a person who fell asleep while watching Ant-Man and The Wasp in theaters, I rarely ever got bored of the episodes, especially with am amazing opening theme to welcome each episode.
This show is smarter than it first lets on, as the characters are surprisingly complex and create interesting dynamics in the team that leave you wanting to further explore them. It deviates from traditional get-over-obstacles-and-always-end-up-beating-bad-guy tropes by delving further into internal conflicts that rival the ones shown on the big screen. The show manages its pacing effectively but still caters to the younger audience with some playful filler that isn't all hard to watch as an older viewer.
Overall, a 9/10 for me, highly recommend that you take some time each day to watch the show. Smart, complex, yet easy to follow and love. It guides you along the way as you traverse through the ever-expanding universe of Marvel. Take care.