I cruised the Marina in Europe, also a few years ago. I found it to be a very nice ship with good food and service. We English speakers were just less than 10% of the ship. We didn't mind so much that the announcements were made in several languages, as the ship's passengers were mostly from different European countries. However, this also meant there was a lot of smoking going on, but it was usually on outdoor decks or in the smoking areas of public rooms. The ship's staff that deals with the passengers all speak several languages. They wear little pins with the flag of the country whose language they speak.
The entertainment was good, and not language dependant. When they did introductions, it was, again, in several languages.
Just make sure you get on the appropriate English-speakers shore excursions!