There was an interesting piece in the Guardian a few days ago by Maya Jasanoff which gave an interesting perspective on the legacy of the declaration of independence.

When Americans look at Britain, they see the monarchy and aristocracy as emblems of an antiquated political system, and champion the US constitution for outlining a near-perfect modern government. But the beauty of Britain's unwritten constitution, at least as Edmund Burke portrayed it, rests in its capacity to evolve over time. This flexibility means that Britain has arguably witnessed more sweeping reforms in the last 15 years than the US has managed in 200. The debate over electoral reform in Britain, for instance, would be inconceivable in the US, where we can't even get rid of the electoral college, a clumsy relic of the 1780s...
The irony is that Britain's political culture, by some lights the more tradition-bound, has undergone a continuous process of change – whereas America, which prides itself on radical revolutionary origins, has gilded itself into an 18th-century cage.