Awesome Art: The background settings and objects, especially during the Fleischer era, are so realistic and well-drawn that you'd expect this to be something from Disney, but bear in mind this is from the same people that brought us the Popeye and Betty Boop cartoons.
Broken Base: There is division over the post-Fleischer cartoons of the series. While some find them to be just as visually impressive as the Fleischer-directed shorts, others disliked the relative cheapness of the cartoons and forced science fiction undertones within the plots. The addition of more stereotypical villains, particularly Japanse and German spies (for obvious reasons), doesn't help matters.
Counterpart Comparison: While none of Superman's usual Rogues Gallery shows up in any of the shorts, the Mad Scientist from the first episode greatly resembles the original Ultra Humanite only with no paralysis. Likewise, the scientist in "The Magnetic Telescope" bears more than a passing resemblance to Lex Luthor, though looks more like Doctor Sivana.
Ear Worm: Superman's theme song/leitmotif, especially if you try to sing Superman's name along to it.
Fair for Its Day: "The Electric Earthquake" has a Native American villain who is a well spokenWell-Intentioned ExtremistMad Scientist type who dressed in either a contemporary urban suit and tie or in laboratory gear, with only somewhat longer hair to mark his ethnic identity. For a 1940s American cartoon, that is a remarkably sophisticated subversion of a common racial stereotype of the time.
Sadly, not so in "Jungle Drums" or "Japoteurs" where the villains get some fairly harsh stereotyping.
Heartwarming Moments: The final short ends with Superman flying past the American flag and giving a salute.
Memetic Mutation: The opening narration, especially "Faster than a speeding bullet", and also "Up in the sky! It's a bird! It's a plane!" The fact that the cartoons were repeated all over the world as pre-film features for years after they were first made ensured that they became catchphrases for multiple generations.
In "The Underground World" Lois and the resident scientist are captured by Bird People and brought to their throne room/altar. They see a near perfect golden replica of the scientist's father who went missing in the caves where bird people live years ago. Then they get tied to a stone, the floor under them splits open revealing a pool of boiling gold liquid and they realize it's not a replica...
Older Than They Think: DC once stated in print that the earliest occurrence of the classic "Phone Booth Costume Change" happened in 1948. In the comics, perhaps — but the Fleishers were there first by seven years in "Electric Earthquake" (1942).
Superman fights a dinosaurian Prehistoric Monster that is bigger than most buildings and smashes everything in its path. Essentially, this episode is Superman vs Godzilla, only 12 years before Godzilla was first created!
Values Dissonance: A surprising lack of this for a WW2-era propaganda cartoon, the native american villain from Electric Earthquake is even played without stereotype, but the African tribe from Jungle Drums... has about the level of racial stereotype you can imagine from this kind of media. As does Japoteurs, which features some outright racist, stereotypical Japanese villains.
Visual Effects of Awesome: The rotoscoping looks amazing, and the animation still holds up well to this day. The special effects work is also particularly notable, such as the battle and subsequent meltdown of the giant laser cannon from "The Mad Scientist".
They Wasted a Perfectly Good Character: Or rather, DC has wasted a perfectly good character. The Arctic Giant can never be called a Notzilla, because it predatesGodzilla. As such, Superman can fight this potentially recurring giant dinosaur time and again, without fear of being sued by Toho, because it circumvents dreaded Internal Copyright Laws. Yet... it hasn't reappeared since its debut in the 40s.
What Do You Mean, It's for Kids?: "Jungle Drums," which is loaded with Nightmare Fuel, introducing images such as barbaric natives attempting to burn Lois alive. (Amusingly, this cartoon made its way onto a "Parent Approved" home video VHS tape of Public Domain cartoons.) The poisoned needle and giant Egyptian tomb guardians in "The Mummy Strikes" are also unpleasant bedtime contemplation for nervous children.