Just finished watching Seasons 1&2 of
Babylon Berlin (sort of one continuous season, honestly). Here are some impressions. Lavish production values, absolutely superb acting from all-German cast, exceptional vistas as the show was filmed entirely in Germany as opposed to Easterner European country as a cheap stand in.
In my opinion, the epoch was nailed to a T. However, there are severe issues with pacing and plot that would prevent me from recommending it. The pacing is awful, the main plot (or the plots) are not well developed and feel rushed and convoluted towards the end. It feels like the whole show is a collection of well acted and directed scenes about folks going on about their lives (characters are well fleshed out), but the story, in my opinion took a back seat.
On a side note, maybe it's my imagination, but the impression that I got that the Germany was doomed in the late-1920s, if it wasn't for the Nazis seizing power than it would have been Communists with the pretty much same outcome at the end. Although, the Reds are shown as persecuted, but are portrayed are far, far from being a "good guys".
In short, if you are a fan of German history of that period, you'll enjoy the show immensely, if you are looking for a story-driven TV show and the setting is irrelevant go look elsewhere.