I`ve played BP in the original beta, and the first 6 weeks or so in Live.
I liked the game very much, and had a great time playing as a member of The Black Hand.
Being unemployed at the time when BP went live I was able to play 24/7 but eventually decided to delete my empire mainly because I really needed to find a job and the game was too much of a distraction.
In my opinion BP had great potential, but was very poorly designed from a game point of view. This resulted in a game that was overly complex, strategically shallow and severely unbalanced. And then Dark Sky Entertainment kept changing the rules for the worse, leading to a mass exodus of players.
I think that design errors are the reasons the game failed. I have made a lengthy writeup called "re-designing BP" discussing the many design flaws and how to best remedy them. It is already on the Sourceforge forum so no need to post it again here.