I liked the production a little bit more than you did, I guess. The innovative direction and acting were able to elevate a mediocre and turn it into a memorable night for me. I agree the the first half of the play- much more dynamic in staging - is much better.
I also shared your reaction to the encouraged screaming. I'm really not into forced participation, and it's just not in my nature to scream. I think people that are more comfortable with that type of activity/participation probably enjoyed it, but I could feel that the repetitiveness was wearing down the audience's response.
My guess that this might have worked better in the UK, where, my impression is, audience is more into gimmicks like this. Think how many British musicals end with a mega mix or a call to the audience to get up and dance.