Don't watch this if you want a satisfying ending.
No I'm kidding. Do watch it just don't expect the ending to give you what you want. (maybe i'm just bitter.)
Also be aware this gets started really slow. However if your a fan of mob movies you'll be used to that kind of thing and probably like this. Actually I think this would be a good anime to show some one your just introducing to the world of anime because it really doesn't have an anime feel to itl It's an animated mob TV series completely with conspiracy, betrayal, prohibition era politics, and of course gun fights. I found the story to be slow and kind of lacking but then I usually feel that way about mafia inspired movies/series so again if you like that genre of western film you'll actually probably like this. I definitely think it was at least worth watching and it was a nice change from the sometimes zany and convoluted world of anime. You should definitely give it a try but be prepared to watch at least through episode 5 before giving up.
The only other things I've seen that I'd say somewhat compare to this are maybe darker than black (one of my faves) and phantom: requiem for the phantom (an anime i hated.) So take whatever you can from that lol.