Senko-san is an anime that aims at a certain audience, overworked and stressed otaku that have a lose grip on reality, but let's start from the beginning:
The Anime follows the life of the standard salary man Nakano, that is basically a 'yes' man pushover that can't say 'no' to save his life. Thanks to that, basically his only character trait apart from his love for fluffy things, he is endlessly overworked in a job where he is seemingly surrounded by bad coworkers that shove their work on him.
Some day a demigod fox girl (that is a 800-year-old legal loli, as the anime never fails to mention) drops into his life and starts pampering him to take away his stress that is so bad it manifests as a black aura around him and starts to threaten to infect other people around him (allegedly, we never see that happen).
That is all you need to know, because that is all that happens. Some shenanigans ensue with sometimes more and sometimes less awkwardness (bathing together, ear cleaning, eating, drinking etc.).
The problem with the show is twofold.
On one hand there are just better anime with similar concepts out there, Dragon Maid comes to mind or Sakura Quest.Those have more character depth and way more general development on every level and while Senko-san has decent animation, it is nowhere near KyoAni or PA Works.
It is just worse than the competition.
On the second hand it feels like the show endorses a lot of bad concepts. There is the implication of 'if you work hard and are overworked maybe you will get a dream wife somehow that makes all your problems disappear without you needing to do anything about your own life', which is clearly problematic and especially worrisome considering the Japanese work culture.
There is also the whole legal loli theme that makes things awkward and plays into certain tastes and is nothing to endorse, at least in my opinion, and most of the show can also be seen as mindless pandering to those questionable tastes.
In the end we have a show that excels at nothing.
The story is non existent. The art, animation and sound are all between 5-7, but the area where the good Iyashikei are weeded out from the bad, the characters, is an utter disaster. The characters are forgettable and worst of all, show zero growth over the course of the show and stay the same for the entire run.
Oh, and I didn't even mention the weird ego perspective parts that are usually situated after the ED with Senko directly talking to the viewers to give the sense that the viewer is the one having Senko caring for...
I can take some pandering here and there, some obnoxious lolis, or some characters that are less than deep, but this show has all of it and no redeeming qualities.
Overall I still give the show an average rating of 5, because the animation and sound is sometimes good and there is no fault in appreciating the work put into those parts, even if it is overall nothing special, but make no mistake this only leads to a very slim 5 that is probably more in the 4.6 area rounded up.
There might be people that need exactly what the show gives you (a legal loli that tells you that everything will be okay), but for everyone else, just stay away, you won't miss anything.