There's nothing wrong with criticizing the president. There's nothing wrong with holding the president accountable for mistakes.
But what has always seemed counterproductive to me is to paint President Obama, the most liberal president in a generation, with the same George W. Bush brush. This approach assumes that both have similar motivations and similar goals and exist within similar sets of circumstances. They don't. That's why Greenwald is more or less correct in terms of values and goals, but is totally and absolutely off the rails in terms of tactics and tone.
Using Bush-era tactics and tone against the Obama administration doesn't make any sense to me. They're two very different leaders, and so our tactics should change up.
Simply put, the tool has to fit the job.
We were effective in helping to shift public opinion against Bush, but our goals with President Obama are very different -- at least, I hope they are. We want to pull Obama closer to our priorities while also holding him accountable. We don't want to drive him away, nor do we want to drive away public opinion against the administration, unless we want President Palin or Romney in 2012. This requires a more nuanced approach and certainly not the outrage we applied to Bush.
But while we rightfully accuse the Democratic Party establishment of lacking discipline, some of the strongest voices in the left blogosphere have succumbed to similar lapses. You know the examples: the apoplectic reactions to anonymous Politico quotes (we should distrust the establishment press, not use them as springboards for outrage without scrutiny), and also the recent use of contradictory memes (He's Just Like Bush and He Should Act More Like Bush), etc... I can't see how this helps our goal of enticing the administration to pay attention to us. If nothing else, it only encourages them to ignore and further marginalize us.
Or as BooMan wrote: "We have clout. But we lose clout when we're seen as uncharitable blowhards."
In politics (and life) every move demands the proper context and perspective, otherwise it's just flailing and noise. And that's wasted energy.