Few people would have been angry about his work if it had not had such an influence.
Derrida could certainly hold onto an idea, but he was not a very good philosopher. His flights of fancy seemed elegant, but were ultimately unproductive - and esoteric, something he made a virtue of.
His 'differance' was what Istvan Meszaros, in another context, called an 'abstract particular' (as opposed to an abstract universal - said, actually, of Lyotard), it existed as an assumption before the fact.
It is one thing to say that you cannot get learning without working at it, but in Derrida's case, there was not much to be got back for your efforts.
Derrida's popularity with what Richard Rorty called 'the cultural left' was not a positive influence. They saw in his obscurantist philosophy the warrant for their own introverted preoccupation with lifestyle and indecisiveness. The much-vaunted 'difficulty' of Derrida's writing was, for the most part, simply a case of meandering around the point. It's study was an exercise in the baroque - the privilege of a leisure class, revelling in their conspicuous consumption of time.
The Stalinist logic that says we should support Derrida because he was attacked by the right loses sight of the fact that he was worse than most right-wing thinkers. At least Roger Scruton, Allan Bloom and Leo Strauss wanted to be understood. In that small step they signalled that they thought more of their readers than Derrida ever did.