I listened in the car. If you hadn't seen last series you would've been a bit lost. And it seemed inappropriate for Martha to be asking how they were after Tosh & Owen in the middle of trying to catch the creature. The relevance became apparent, of course.
I was waiting for a Ferero Rocher joke too. DIdn't come away disappointed there
You needed to have watched the television series to make any sense of it. I enjoyed the play - but found it hard to suspend my disbelief of a monster that ate neutrons - and bodies left behind glowing and intact but becoming less dense. Even for Torchwood, it was full of (black) holes. (And I speak as a long time fan of Dr. Who, Torchwood, Star Trek etc.)