We did Southamton to Rio (including the Amazon).
We found Adonia to be well appointed, with a good library and card room.
Good points :-
Tea/coffee facilities in room (we haven't had that on other ships)
Drink prices reasonable and NO 15% service surcharge.
Amount of money deducted for tips very reasonable (In fact we gave our cabin steward and waiters extra).
Excellent, friendly staff.
Bad points :-
Internet service expensive and virtually unfit for purpose. (I spent almost 100 minutes to get one Email sent! Then had to make a bit of a nuisance of myself to get full refund).
Too many formal nights (7 out of 32)
No ice cream parlour anywhere on board.
Seeing stage in theatre/lounge very difficult unless you're near the front.
Entertainment - Guest acts average to rubbish. Ship's theatre company -average
Guest speakers - Excellent to poor.
On board activities - somewhat limited unless you're into quizzes and dancing.