It's a great show, I've been following it since it was a collection of shorts with no plot whatsoever (where the whole routine of Retsuko loosing control over her anger made more sense).

The anime is great but I wouldn't reed to much into it: it's an unfiltered vision of a woman's life in a modern day Japan, between "old school people" like Ton the pig, with all the prejudices that people of his age usually have, and the need to find a purpose to be happy. Retsuko does what most women do in Japan: chase a relationship for the sake of getting married and finally leave the job. But it's not so simple both because love is something hard to come by, and because she does not even know if she wants that. She knows she hates all the stuff she has to suffer at her workplace, that's for sure, and marriage is the traditional escape plan.

The show peak at the latest seasons, namely the forth and the fifth, with what I consider to be the lowest point in the third season.

It's an incredibly honest depiction of how real life Japanese society works, with all the flaws and the imperfection not being hidden: exploitation at work based on seniority, social pressure to marry and quitting your job, lack of meritocracy in the hierarchy of a working place, and many more I'm not quoting for spoiler reasons.

You are right OP, people don't talk about this show enough. It's very good.