We were on the same 8 day sailing of the Explorer as the OP and can say it was not one of our favorite cruises. The crew was working very hard, but there just were not enough of them. We spoke with one waiter who said they need an additional 30 waiters.
I think the shortage of crew affected dining the most. Izumi and Johnny Rockets were only open for lunch and service was slow in Johnny Rockets the day we had lunch. The fellow who was in charge of Johnny Rockets was actually acting as a waiter for several tables in the dining room at the late seating each evening.
I know that the cruise line needs to have high occupancy in order to make money, however having high occupancy without a full crew will only result in complaints even though the crew is doing their best. Many posters on Cruise Critic are fortunate to be able to take multiple cruises a year. For us, these temporary problems will not mean much. However, those who save to take a cruise once a year or every few years, may not come back because they may feel the current service is what is always provided.