We've just finished the Avalon Lower Danube cruise (Bucharest to Budapest).
We did the Transylvania extension before joining the cruise - really good.
The ship was meant to depart from Fetesti, but due to low water levels, we departed a day later than planned from further upstream (Turneu Magarele in Romania), and so Avalon is refunding 1 night's accommodation, meals and gratuities cost as we only got 8 nights on the ship instead of 9. We had to miss out Constanta, as too far to drive from Transylvania so we had an extra night at the Athenee Hilton in Bucharest, with a tour of the Parliament, and Ceaucescu's house, before driving 2.5 hours to the ship. The rest of the itinerary operated as planned and we sailed to Budapest. Enjoyed the trip (apart from the boarding experience), the weather was very hot and evidence of drought in all the countries visited. Let me know if any questions!