This wasn't our first river cruise. We did the Rhine last year. Both vacations were amazing, but the Rhine wasn't as popular/crowded (fewer ships).
The Danube was high due to recent rainfall and bridge clearance was an issue. Avalon did a great job of working around difficult conditions.
The quality of the shore excursions depend, in large part, on the local guides. Many of the guides were entertaining and knowledgeable but not all of them.
Cabin was great. Plenty of room and very clean.