Dororon Enma-kun Meeramera is an anime adapted from the same namesake manga from the 70's. And most of the content and structure stems from that period. As a gag/ecchi anime/manga DEM certainly displays the mediums juvenile tendencies in its fullest, the good and the bad. The best thing about this anime is probably the structure and artwork. For most of the time the art is stylized in a constant quality, if necessary. But most of the time it has a decent animation over the whole run. The structure is similar. It starts with a monster-of-the-week approach, but as more characters are introduced, the higher the stakes becomeand the mystery about the attacks of the weekly monsters become more apparent.

However, this is where the good things end. By far the weakest link of the series is its comedy. It is 70's. In that era vulgar displays of nudity and genital humor were considered funny. But, 40 years later for the anime release and 50 years by time of writing this, it no longer is considered funny in that region as more nuanced humor was established culturally. The internet changed a lot in that regard and while I don't blame it for this downside, it certainly changed the perception of what is acceptable and what not. Still, these differences are still within different countries as their culture is still a part of what is and is not funny or engaging.
And while some might think that having a penis sword in the first episode might be considered as rude by some, I merely considered it as something weird but ultimately a skill the demon has, even when it isn't practical in any sense.

And this carries through the whole series. As someone who wants to enjoy stories on a more nuanced I certainly am not part of the target demographic of this series and thus not really qualified to talk about subjective experiences of comedy.
However, and this is a big one, certain aspects and sexual comedy has universally changed through most of the modern countries. In this anime, there were multiple jokes involving rape and zoophilia/bestiality. And these points made it clear for me that this anime shouldn't have been produced in the modern time, or at least changed for these points.
Other than that most jokes border on the lines between fine, boring by repetition or boring by duration. For me there were no outbursts of laughter in none of the episodes.

In regards to the characters, there isn't much to talk about. All of them fall into certain stereotypes to facilitate the comedy. Pervert protagonist, love interest by being opposite, slapstick character, wisecrack and fish-out-of-water. They all have their contrivances and while they bring different aspects and viewpoints to different scenes, they still all fall in the predictable section.

In total Dororon Enma-kun Meeramera falls flat through outdated humor whose comedy has fallen out of favor of the modern times and would mostly be regarded as something that exists. Most of the jokes are predictable through the stereotypes the characters portray, but some jokes are, while not offensive, have simply aged very, very badly. Comedy certainly is subjective in many regards and one has to be in the mood for the comedy to be allowed to make an impression. As someone who isn't the target audience, and doesn't even want to be, it didn't resonate with me at all.