We tried for the AX category, but finished up in one of the two A-Class cabins that are right at the back of the ship, up against the door to the crew quarters.
Apart from the lack of a tub the voyage itself, from Magdeburg to Melnik, was too short: the ports of call are enthralling, the often wild scenery and general topography spectacularly beautiful. 'Saxon Switzerland' is extraordinary. The wildlife is very impressive and includes some species which we had seen neither in Europe nor in N. America. We did not take the guided tour of Torgau or Meissen; in the latter place we climbed up to the castle and cathedral instead, which are very fine. With an AX cabin we'd love to do it again, spending if possible an extra two nights on the boat.
The food was outstanding as usual. Round tables for dining would be more sociable, but we realise that this might not work in the space. The staff were all friendly and efficient.
Both the Berlin and Prague 'legs' are really good, and it's worth buying the extensions at each end. This still gave too little time in either place. The extensive Berlin and Potsdam tours are superb value. The Berlin Hilton is well-placed, the Prague Hilton good but too far from the centre.
We carried a laptop computer. A minor irritation was that Viking's Wi-Fi provider seems to have a quarrel with Telus, so e-mail can be received but not sent. Free Wi-Fi did not obtain during the extensions, and that was expensive.
The communications gear on the guided tours could usefully be set up for people using a hearing-aid.