To me, Hotel Beau Séjour was probably the best show I've seen on Netflix, and the best whodunit/thriller since The Killing. It's never dull, doesn't get soapy despite its length and isn't full of the clichés that make story telling easy, but characters unbelievable. The acting is very natural, and the production level is high, certainly for Belgian standards, where the budgets are rather small.
The plot is not the series' main strength. In fact, I thought the final bit of detection was the weakest point.
Instead, the series' strength is the telling of the everyday lives of ordinary people, sucked up in a world they don't completely understand and control, and how that can lead to the death of a young girl. It is a story of weakness, the weakness that defines the human condition. The whole business is common and sordid, but can only be told by showing the entire context, from the laissez-faire attitude of a farmer via the failures of a drunk headmaster to the clumsy sexuality of a simpleton. The truth can finally only be seen through their despair and helpless attempts to make something out of their lives, and the writers can only be praised for making almost every character a round and integral part of the story. In that sense, this series provides a deeply compassionate view on society and all its flaws.