We went in September 2011 and booked the least expensive cabin on the lowest deck. I believe that the cabins are identical except for deck. It was fine with a tiny balcony, big wall closet, big bed, big bathroom. We're not too picky except for cleanliness and it was. Food was just OK. It was buffet but at dinner you could also order ala carte. The menu was in Portuguese and the head waiter would come to our table talk to me for 5 minutes in Portuguese and then I would nod and say "fish". I don't speak anything but English. We always got good fish. The ship was empty so I don't know how service would be if it were full. We really enjoyed the trip but I don't believe that the ship comes anywhere close to a Silverseas ship.
We took Celebrity Expedition to the Galapagos the previous year. It was wonderful.