As for the Treaty of Heidegger, it is obviously one of the key books of the twentieth century, one of the ten / fifteen most important books in the history of the Philosopie, to store next to Aristotle's Metaphysics or Phenomenology of Spirit Hegel.
As for the translation, it is almost impracticable, and closes access to text instead of making possible: you absolutely prefer the translation of Emmanuel Martineau.