I'm reading them just now - I find detective novels and sports papers to be good ways to learn languages, since there's some common structure to the stories. Also, the kindle store has a _very_ limited selection of foreign language texts[1], but they do have the complete Maigret, in 6-novel volumes, so you can get em cheap. (Others I've been reading are Vargas, Leblanc, Montalbán - Paco Ignacio Taibo II is next on the list)

Another striking thing about Maigret is how much he relies on the police force around him. Today we expect the detective to be a loose cannon, at odds with the department, but Maigret is constantly asking others to surveil and report, the spider in the web. There's only a couple of early stories with hints of a difference - where he notices something odd and ends up following someone on instinct. (Le Pendu de Saint Pholien, La Guinguette a deux sous)

Also - mentioned in the article - but there's a lot of boats! Simenon wrote quite a few of these early novels on board boats and it shows, trawlers and narrowboats abound.

[1] 10 years ago I was able to buy novels on amazon.fr while in France, but this stopped working? It wanted a delivery address and credit card in the country as well. I was cycling round the country back then and ended up buying paperbacks at flea markets instead.