Some of the cartoons showcase Superman's timing in stopping whatever threat is in play as oddly lax, usually waiting until either Lois gets involved or until Clark is directly affected. Case in point, the titular villains in "The Bulleteers" manage to destroy Police Headquarters and demolish the City Power Plant, causing a citywide blackout, before Clark ever gets involved. This can be a little jarring for people who see Superman as a proactive force for good.
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 Famous Studios 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.
Counterpart Comparison: While none of Superman's usual Rogues Gallery shows up in any of the shorts (a great number of them didn't exist back when these were made), 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 his visual design is closer to that of Doctor Sivana. Also, while visually different, the villain of "The Mechanical Monsters" operates a lot like the Toyman.
Ear Worm: Superman's theme song/leitmotif, especially if you try to sing Superman's name along to it.
"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. The latter is at least somewhat understandable (Pearl Harbor and America's World War II entry happened during the run of the series, and "Japoteurs" is a typical propaganda piece of the day) but still very unfortunate and sad to see in hindsight.
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 "The Mechanical Monsters" (1941).
"Terror on the Midway" features Superman doing battle with a Killer Gorilla called Gigantic seventeen years before the debut of Titano.
Values Dissonance: In 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.
Even Electric Earthquake, while certainly Fair for Its Day, is still based on a strawman of Native American rights activists, probably based on (completely unfounded) white anxieties around the Indian Reorganization Act.
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 International 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.