My husband and I along with another couple took an AMA Waterways extended Danube cruise this fall, which started far from the Danube in Istanbul and ended somewhat past the Danube in Prague. There were 14 actual days on the ship with an almost total turnover of passengers and some crew in Budapest.
There were many highlights -- several on the land extensions. Istanbul and Prague are both bucket list cities and live up to their billing. The illuminated night cruise of Budapest was exceptional and there were a couple of surprising charmers (Bratislava and Pecs come to mind). There were some lowlights as well -- being bussed through northern Turkey and across Bulgaria could be skipped. The hotel in Bulgaria where we spent the night (a Ramada) was truly the worst hotel I've ever stayed in, and I've lived in Asia. Actually, touring the poorest part of Bulgaria, Serbia and Croatia from the Danube is educational but not necessarily entertaining.
The AmaPrima was a nice enough ship but oddly designed. The small "library" was sparsely stocked with a few random coffee table books but no matter, with the little low-voltage pin dot lights, you could barely see to walk much less read. A built-in buffet station in the middle of the main reception room made the frequent all-ship briefings and onboard entertainment awkward affairs as the space was broken up by this massive buffet. Putting the buffet station at one end of the room or the other would have made much more sense. For a relatively small ship, more attention should be placed on maximizing form and function.
The staterooms (I'm told this is true of all riverboats) were miniscule. Although we booked a year in advance, all that was available were on the lowest level. We were told that we were on the wait list to upgrade but at sailing time, that hadn't happened. The "Piano" level is akin to steerage. The rooms are so small that to get to my side of the bed, I had to crawl on the bed because there wasn't room to get around the desk that was crammed in. Also, when you go through the locks, the noise on this level is uncomfortable to the point of unbearable.We did manage an upgrade the second week, which was somewhat larger plus had a small balcony. But on the two upper levels, the bathroom has a transparent window that becomes translucent when the light is turned on. The trouble is that the light and window turn on whenever someone opens the bathroom door, thereby waking up the other person should you have to go to the bathroom in the middle of the night.