Considering the recent financial crisis and the issue in the United States with banking and the example of NORTH DAKOTA which doesn't have the problem the rest of the states are having, it seems to me there is a definite advantage to having a state owned bank.
It has been a long standing war in the US with the private banks enventually winning that war in 1913 with the creation of the Federal Reserve system after the meetings at Jekyll Island, and the quiet introduction of the income tax (interesting coincidence).
As it stands, it would appear the private interests have enormous control over the financial system and even benefit unjustly from it as I have often asked: who gets the new money when new money is created by the fractional reserve system?
As far as I am concerned, governments ought NOT to be in the banking business, strictly speaking, but the banking system has changed away from savings and loans, towards -national- money CREATION. Until that problem is fixed governments need to be involved in banking. I had to specify 'national' money creation above, because there is no reason that private banks or other institution cannot produce their own local money in principle.