Yes, very tough, though not as tough as Sabre or Quinapalus, which is some relief. The second instruction helped me fill one blank cell that was part of an unsolved clue that had been baffling me for ages, partly because the cryptic syntax seems a bit clunky and out of keeping with normal Listener syntax. Perhaps I've misunderstood it.
Given the constraints of the sets and the twin messages, the clues were a really excellent set, though some indirect or cryptic definitions made solving difficult in places. The grid is also a magnificent achievement, with very few unchecked cells.