I was also on this cruise and agree with the OP on maintenance of the ship, entertainment and disappointment in missing ports.
I was also surprised at the enforced table sharing in MDR for breakfast and lunch - even during a bad norovirus outbreak on the ship! Also, I found it worrying that there were no staff available for cleaning or sterilising tables in the buffet or bars between guests, and yet Noro cases kept raising....maybe the two are connected!
It was my first P&O cruise and I'm not sure I would book another. If I did, definitely wouldn't revisit Arcadia.