Certainly one of the biggest boondoggles ever. At an estimated cost of $150B through 2015, that is $24 million per day! (based on 6250 days by end of 2015). Extending the math, that is just over $1.5 million per orbit.
And for what? What inventions or unique processes have been discovered or perfected and put into use on earth to better our own lives? What scientific results have been significant? (I won't even ask for memorably significant) What non-human experiments were done what could not have been done far cheaper by other means? Did the TV news ever lede with "An incredible scientific breakthrough by astronauts/researchers on ISS was announced today...."
Using just a third of that money, NASA (and lets be honest, almost the entire cost is paid by the US) could have spent over $6B more on exploratory missions to each of the other 8 planets (including Pluto). And still had $100B left over to spend on projects, scientific or otherwise, at home.