The downside is the new DM had to deal with it, and I could see the frustration in his face. I tried to help by setting an example and trying to keep things focused, but there's only so much one can do. A couple of times he was delivering a dialogue from an NPC and one or two other people literally continued their side conversations right over him.
I think part of the problem is our group is too big. We have 8 players + DM. An 8 player party is HUGE, in my opinion, and has several side effects:
- More people means the DM has more to do keeping track of everyone
More people means combat encounters go much easier and thus, less exciting
Experience is divided more ways, resulting in smaller rewards for each character
Same for treasure.
More people means it's easier to get bored from not having anything to do, and that inevitably leads to side chatter, mobile devices coming out, etc.
The ideal D&D party size, IMHO, is 4 - 6. That's enough players to cover all the archetypes at a minimum, with not a ton of redundancy at the upper end. This is the party size most printed modules are designed for.