We found this trip quite interesting in the contrast between these recently communist territories and surrounding non-communist countries/cities. Our tour directors were mostly young and were children at the time of German reunification and the Czech "velvet revolution", but told us interesting and very real stories of how their parents and, often, grandparents were affected.
Most cruise stops were "quiet" (the whole river is compared to the Rhine or Danube) but interesting. This particulat cruise had about 60% representation from the UK (most others were Americans plus one Aussie couple) and were a generally older (average age probably 75-80), but very "game" and interesting group! We thought the age factor may have been due to the "easy" rating to the tours and possibly because of the WW II history connection to this age group. We ended in Prague which was fantastic, but crowded, as usual.
Ship was excellent - well-maintained and clean - and the staff was particulary friendly and helpful. Our program director (a young Czech) was particularly notable. Food was good+, cabin was upgraded and was spacious and comfortable.
If you're interested in a cruise with a recent history bent in addition to the usual European history, you might find this one interesting.