I can't say enough about the Europe-Black Sea cruise we took on the Prinsendam in September/October, 2013. The small ship was absolutely fabulous: service, crew, ports of call, entertainment and food were outstanding. We have sailed on several of the Holland America cruise ships, and while all of them have been lovely, the Prinsendam is, without a doubt, truly special. They treated us like family and took care of our every need. Our cabin was a lovely ocean view room - very spacious and comfortable. From our cabin steward to the chef in the Cafeteria, to the cruise director to the Captain - every single one of them were exceptional. If you're looking for a small, cozy, intimate cruise, I would highly recommend the Holland America Prinsendam.
The ports of call were especially lovely: France; La Specia/Cinque a Terra, Obla and Brindisi, Italy; The Greek Islands of Hydra, Mykonos, Rhodes and Lindos; Isanbul, Ephesus, and Meteora, Turkey; Kotor, Montenegro; Romania; Socchi, Russia and the Ukraine. What an amazing trip. We opted to take off on our own and rented cars and motor scooters in most of the ports and saw even more on our own than if we would have taken the ship's shore excursions, and much less expensive. If you're adventurous, I'd recommend spending some time on line investigating the different ports and then exploring on your own.
In Kotor, do not pass up walking the 1600+ steps to the old fort - it's definitely worth the effort. Take the train in La Specia to Cinque a Terra and just stroll the small towns - beautiful. The only place that you might want to take a tour or hire a guide would be Ephesus, since there's so much history that unless you have a book or guide, you may miss a lot.
I just can't say enough or recommend this trip highly enough - it was truly a cruise of a lifetime.