No doubt still a good show but back when it premiered, I think people were expecting way more (set during an interesting era with a solid budget, made by some of the people who were behind The Sopranos, strong cast etc.). It kind of became less popular with each season and you can see them rushing the show at the end.
I think a big problem was Nucky, Steve Buscemi is a good actor but Nucky was never that interesting. The most intriguing part of the character was him being a politican and a gangster at the same time but that was basically dumped after S2.
Characters like Jimmy Darmody (killing him off too early was a big mistake, easily the most compelling character), Al Capone, Arnold Rohstein etc. clearly stole the show yet the writers kept focusing too much on Nucky.