In my country this was broadcast in eight episodes of a bit less than an hour each, where each season in Havana, which equals 1 murder mystery, was split into 2 episodes.
The good part: if you (like me) are a fan of Havana's special atmosphere, with its old 50s cars, revolutionary murals, and decaying colonial-era houses, then it'll be worth your while watching the show and you'll enjoy every minute of it. We get beautiful Havana landscapes, amazing drone shots, views of streets and neighborhoods both poor and rich, peeks inside grand houses of yesteryear, some in better condition, some in worse, old telephones, wonderful decor. The colors, the atmosphere are stunning.
The people part is also great - we get to see beautiful Cubans all around (and they are very beautiful), along with some less beautiful of course, but that's life. We also get to see most of the beautiful ones having sex, and they make a great sight.
Still on the positive side, themes that might once have been taboo in Communist Cuba are freely discussed, including drug use in schools, official corrpution, people escaping to the U.S., past repression of homosexuals, drag queens, parodies of the official ideology ("machismo-leninism" was a good one), etc. The impression was that nothing was off the table, even for this production which is Cuban-Spanish.
Now to the weaker spot: the 4 actual police mysteries. Without giving anything away, and without being an expert in police dramas (as it's not my favorite genre), I found their resolution to be very simplistic. At first each murder looks really baffling, with many suspects and no clues, and then at some point towards the end, one of the suspects breaks down as if by magic and tells everything, where they really didn't have to. A bit disingenious, and disappointing.
All in all as I said I'd recommend the series for Havana fans, just for its color. To me it was a pleasure to watch and made me want to go back and visit.