We were on the Grand Princess in March. It is a very nice ship but large. The service
didn't seem to be that personable but I found that on the Exploreer of the Seas also.
Since you have so many people the service is a little lacking compared to the 70 ton
ships. We did Personal Choice dining for the first time and really enjoyed it. You have
a choice to sit at a large table and you will get seated right away. There was couple of
nights when we wanted to eat alone. They give you a beeper like they do in restaurants
and wer didn't have to wait more than 15 - 20 min. You can go anywhere on the ship.
It definitely was comparable to RCCL's Explorer of the Seas.
We just got back from the Grand on Sunday. Great ship! We had Personal Choice dining, and loved it. We ate when and where we wanted.
I have never been on the Explorer, but I have been on RCCL's Speldour of the Seas, and I have to say that it is a different experience (both pleasurable, but different). The only other mega ship I have been on is Celebrity's Millie, and I would say it is more like the Grand than the Spleandour (basicallly just because of size).
I don't know what RCCL ship you have been on, but if it is one of the larger ones, I would say that you will find it comparable.