Other have tried to put it in perspective - throwing water on the idea that he's behaving lawlessly.
He's issued fewer executive orders than other recent presidents:
Pages added to the Federal Register per year are the same - more or less - as those under W Bush:
Here's a comparison to past president's who used executive power broadly:
In short - Obama's actions are probably best seen as part of a general trend towards expanded executive powers. For better or worse.
These are push-the-envelope moves but strike me as within the bounds of the modern presidency. Some historical perspective:
First, the constitutional tug-of-war between the president and Congress is as old as the republic -- indeed, an essential element in the constitutional design. The framers were wary not only of creating a monarchical chief executive but also one hobbled by congressional interference.
Second, there is a robust history of presidents pushing ambiguous constitutional boundaries to engage in unilateral action. Jefferson executed the Louisiana Purchase despite his own doubts about its constitutionality.
Lincoln issued the Emancipation Proclamation, notwithstanding the Constitution's recognition of slavery and his own concerns about the proclamation's susceptibility to legal challenge.
Third, this trend toward broad presidential power has accelerated in recent decades, under presidents of both parties -- even before George W. Bush's aggressive use of signing statements, and his war on terror.
In a 2001 Harvard Law Review article, Elena Kagan, a veteran of the Clinton White House, traced the growth of presidential power over regulatory agencies to Ronald Reagan (in pursuit of efforts to loosen regulations) through Bill Clinton (in pursuit of more activist government, a way around a balky Congress, and political credit).
Clinton's unprecedented interventions, she wrote, represented a "significant enhancement of presidential power over regulatory matters."
Fourth, assessments of presidential overreach are inherently matters of situational ethics: How you judge whether a president is overstepping his authority is inevitably colored by whether you agree with the substance of that exercise.
Put more bluntly, much of the hoopla about presidential imperialism is politics dressed up in constitutional clothing, to be put on and off depending on which party holds the White House.
Thus, Democrats condemned what they saw as Bush's unilateral excesses, while Republicans remained largely silent and unconcerned. Now, the roles are precisely reversed.