It must hold its own. But it can't be too pushy. It has to be a good neighbor - in a very big neighborhood. Far more people see art in public spaces than in museums. The success of public art depends on planning, ambition, and financing.
Good pieces suit the scale and the mood of their settings.
They go beyond illustration to tell you something you don't already know. They can be expensive. But when art is part of a larger construction budget, the money is usually a drop in the bucket compared with overall costs. It's a lot easier to find contemporary public-art failures around Boston than pieces that truly work. Boston's particular problems with public art are multiple.