Well, I stuck with it for two seasons and feel cheated. Some good acting, though even Steve Buscemi has had his moments of wtf acting. Some great costumes and sets and camera work etc. But the story line became more and more preposterous. Something out of exploitation movieland, like I can't come up with a reason for drama so let's kill someone.
I've already posted about the cynical outlook on life and humanity the show portrays, but the saddest thing about it is all the over the top too violent for Greek drama scene ravaging comes from the made up parts. If Scorcese and the rest had had the courage to stick to the real stories of the characters based on real people it would have been a much more interesting look at boss-style politics in the 1920s (in this case Republican) as well as race and religion and ethnicity and Prohibition with perhaps some relevant lessons for our own times.
But they took the easy way out and went for the blood and distortions of what actually was truly interesting and dramatic history. Where are the insights into our history through realistic drama when we need them?