We chose this cruise because of the stop at St. Petersburg. We also booked a two day excursion through Princess and were very satisfied with the experience. The start at Copenhagen and later a stop at Tallin and Warnemunde/Rostok (we didn't go to Berlin) were new to us. The other countries, Sweden, Norway and Finland we had visited before but enjoyed going back again. We have traveled Princess for 6 trips all over the world and they are a good solid cruise line.
The overall experience on the Regal was good if you subtract the introduction of the Medallion program. No matter what you read, this program is in it's infancy and very buggy. In our opinion, of course. The problem is that the marketing department touts all that the program can do but when you as a passenger are trying to use the various apps - it can be extremely frustrating. Why? because other than getting you into your room and on and off the ship it only works as advertised 50% of the time (at best). We and our 7 companions on this cruise all ran into similar problems. If you are not technologically sophisticated, forget it, as it stands, the Medallion program will drive you nuts.
OK enough on that topic. The staff on Princess are top notch! And this cruise is no exception - from our cabin attendant to the dinning room staff to bartenders, etc. all make you fell pampered and appreciated. Even staff that have no direct relationship to you make a point of saying hello. Entertainers were great and every evening we had something to do that was fun.
Food - this is a bit dicey because my wife and I don't eat meat, chicken, turkey, etc. We do eat seafood, some eggs and cheese. So my comments are based on our experience as semi-vegetarians. In general the vegetarian options in the dinning rooms are carb heavy and very light on acceptable protein. So if you are like us, plan on spending time at the Horizon Court where you have a wide selection of excellent vegetarian friendly choices.
In closing you can't go wrong with Princess but at this point we suggest going in with no expectations for the "Medalion" program and be pleasantly surprised if things have improved by the time you sail. We have another trip booked in the Mediterranean in 2020 so we'll report back then.
We had a balcony on the Dolphin deck slightly aft. Good room, nicely appointed but it seemed smaller that previous Princess ships we have sailed on. Anyway, certainly adequate and comfortable for two people. Very quiet and relaxing.