I am aware that this may seem rather naïve, but I feel I must ask it anyway: Are Heidegger's meditations on "Being" in "Zeit und Sein", and Derrida's deconstructions of Lacan's Freudian reflections on structuralism circluar? If Wittgenstien (later work) is applied to both, surely neither hold credance in terms of progressive thought - or was that their essence of what they were adressing?
I'm not overly familiar with Heideggers thought, however a review of his Basic Concepts of Aristotelian Philosophy states that
despite the revolutionary impact of Being and Time, Heidegger developed some of his most central ideas by the most traditional of routes: commentary on the Philosopher.
For example, in De Anima Aristotle suggests that one of the markers of consciousness is an awareness of time - so 'to leap ahead'; this is quite suggestive given how H rephrased consciousness - Dasein - that being for which being is a question.
Heideggers prose, it seems to me, lends itself to bad translations, hence the charge of obscurity becomes self-fulfilling: bad commentaries on bad translations; the recent translation by Joan Stambaugh is particularly clear.