The Demon Girl Next Door is great. I love it and it blows my mind that it's based on a four-panel manga, because its plot and character progression are excellent. This, though, is a spin-off of a form I've never seen before. Thirty-second episodes, more or less. On average.
Is there any point in watching it? Well, not if you haven't watched the parent show. You'll just see characters you don't know appearing briefly and exchanging a few sentences. If you don't already know and love Yuuko/Shamiko, Momo and Lilith, forget about it. Fortunately, I do, so I watched all the episodes. It doesn't take long. Sometimes, they're amusing. I laughed a few times.
There are three series:
1. MACHIKADO MAZOKU MINI (34 episodes)
Roughly what you'd expect. Lots of short conversations, which on reflection I imagine are direct adaptations of the original comic strips. Thinking about it, that must make this the most faithful anime adaptation ever of a 4-panel manga. No reworking into a longer format. No reinvention for another medium. Exactly the same length. Exactly the same jokes.
I did notice, incidentally, that all the magical characters have something on their head. Yuuko/Shamiko has curly goat horns. Lilith has longer, straighter horns, although one of them is broken. Momo has a flower hair ornament. Mikan has a side bun.
It's gentle humour and most of the episodes aren't funny, but they have their moments. Ep.13 made me laugh.
2. UGOITE HAMIDASE! MACHIKADO MAZOKU (12 episodes)
It's like a shopping channel. Lilith in her doorstopper form is the narrator/salesman, while more visually interesting images appear in a box next to her.
It took me a while to notice that these micro-episodes have almost no animation at all. Made on the cheap! Lilith bounces a bit as she talks and there's some scrolling text along the bottom, but the image box is a small montage of still images. That said, though, that doesn't really matter because Lilith's voice actress (Minami Takahashi) is fun to listen to.
3. YORINUKI MAZOKU (23 episodes)
This was the most interesting for me. The camera pans over panels of the original manga while voice actresses deliver the dialogue. This is theoretically a bit like furigana (which the manga doesn't have), but in practice it's completely different because you can choose your own pace when reading furigana, whereas here you've got actresses with natural, energetic line delivery. It's a speed challenge. Can you read the manga's dialogue (including kanji) and keep pace with the actresses? You've also got the interesting juxtaposition of the occasional times when the actress's chosen line delivery seems slightly different from what the mangaka had been imagining, given the balloon outline and font weight.
Are these micro-episodes good? Individually, not really. It's very, very hard to do a genuinely good standalone strip in four panels. Garfield or Peanuts work, for me, because I have collections of them and read an entire book at once. (It doesn't take long.) Add up all these episodes, though, and you've got something that I might, perhaps keep. The characters are charming, e.g. when Yuuko extends her death challenge to the weekend, or invades Momo's apartment in order to do some cleaning. I love the main anime, after all. I'm surprised and delighted that it's getting a second season. Everyone should watch it. (This, though, maybe not.)