I saw the Menier production (i.e. this production, but in London) and the reviews were the best ever for a Sondheim production. Yet during the first number I thought, "Oh my god, this is so over the top, I'm going to hate it. Is this a British thing where they have to telegraph everything so loudly?" But then, as the poster above points out, it got stronger and stronger. I decided that a decision was made to make the opening number very "big" so that everything could get across to the audience--then they could follow the rest of the show. As an aside, when I saw Hamilton in London, the actors were pronouncing the opening number so carefully I, again, thought "oh no, have they dumbed this down for the UK?" But the show really picked up. I also thought then they were just being careful for it to be understood--and of course, the actors were British so while their accents were good, they didn't really have the casual street sound of the New York cast.