Common Sense has given this show a very bad rap, one it doesn't deserve.
SRMTHG is a much deeper show than the mindless laugh tracks being passed off as cartoons these days; true, there are comedy episodes, but it has continuity, a strong, deep plot, dynamic characters, love (in both senses of the word) and life lessons that children can learn.
We have a very strong cast of flawed but ultimately good protagonists: Chiro, the young teenage hero, at times cocky but sensitive and considerate of his comrades, Antauri, the black, later silver monkey (after his death and resurrection), who behaves as a wise mentor and kindly father figure to Chiro, Gibson, the blue monkey and resident genius, Otto the green monkey, a mechanical wizard who is very good-natured and kind, Sprx, the red monkey, comedian and occasional ladies man (who is later revealed to be in love with Nova), and Nova, the yellow monkey and only female main character, who is at times short-tempered, but is very loyal to her friends.
The show is highly intelligent (just look at Antauri and Gibson's diction, if you want a prosaic example), and is 'not' a purely violent, cheerful show. The "I, Chiro" saga, consisting of the episodes "Antauri's Masters", "I, Chiro", and "The Savage Lands, Parts 1 and 2", are deeply engaging, very dark but at the same time the best example of what SRMTHG has to offer. "I, Chiro" in particular is possibly the show's most popular episode, an edge-of-your-seat tear jerker.
SRMTHG gives a lesson that very few young children learn from watching run-of-the-mill cartoons. Bad things can happen to good people. What happens to Antauri in "I, Chiro" is an obvious example, but what I'm thinking about is the Alchemist's fate. The Alchemist, a good man with only the best of intentions, did not do anything to deserve being tainted with the evil that would transform him into the Skeleton King, but it happened anyway. Because of this, he created the Hyperforce in order to defend the universe from what he would become. Despite growing deeply attached to the monkeys, especially Nova (whom it is hinted may have been the Alchemist's favorite), the Alchemist erases their memories of him so they will have an easier fighting him in future; this decision deeply saddened him, but he went through with it later. The point is, after learning the truth about who the Skeleton King used to be, even with how ruthlessly evil he is, it's never possible to look at him quite the same way again. A quote of the Alchemist's sums it up nicely: "I beg of you...remember me as the person I was. The person I am."
All of the monkeys, and Chiro, love each other, but I wish to elaborate on the three deepest relationships: the relationships between Chiro and Jinmay, between Sprx and Nova, and between Antauri and Chiro.
Chiro and Jinmay are the typical teen romance (if very sweet and chaste), having essentially been boyfriend and girlfriend from the first day they met. They prove that long-distance relationships can work. Sprx and Nova are the more "adult" romance (still very chaste; this is a kid's show, after all), having been built up for a long time, with delicious tension between the two at times. But Antauri and Chiro's relationship is my favorite.
It's not romantic love, by any stretch of the word. Even a casual observer of the show will quickly see that Antauri and Chiro's relationship and emotional dynamic is clearly that of father and son, arguably the strongest relationship in the show. Antauri's attitude towards Chiro is at times stern, at times kindly, at times nurturing, but he always behaves with Chiro's best interests at heart; Chiro consistently deeply respects Antauri's judgment and, for the most part, does not question his word. Since it is speculated that Chiro's parents are either dead or otherwise emotionally unavailable, it is entirely possible that Antauri has become a father figure to Chiro when his parents can not fill that role. If anything, Chiro's reaction in "I, Chiro" and "The Savage Lands", to Antauri's death (before his resurrection), definitely has parallels to a child's reaction over the loss of a parent; it's enough to have had most of the viewers in tears the first time they watch it (And sometimes in tears for subsequent views, as well). At any rate, Chiro definitely looks up to Antauri as a teacher, if not as a father, and Antauri's behavior and choices when it comes to Chiro is at times much more responsible than the choices made by many human parents today, despite the fact that he's a monkey.
But my favorite aspect of the show comes from an exchange at the end of the first season finale "The Skeleton King". The Skeleton King appears to have been killed (he really hasn't, but it doesn't detract from this conversation at all), and Chiro comments that he can't imagine a world without the Skeleton King. At this moment, Antauri and the rest of the hyperforce appear, with Antauri saying "Of course you can, Chiro. You have but to choose to." He's basically saying that it is possible for there to be a world without evil. The spirit of optimism manages to shine through, always.
SRMTHG is a must-see show for children of all ages, and I think that adults will enjoy it too, for its deeper messages, despite what this website says.