Just stayed 4 nights at what is now the Belmond Hotel das Cataratas and was very impressed. Admittedly there may have been an element of relief after the rigours of Pantanal travel but I do believe this property is of the luxury persuasion even if it isn't a great star in that firmament.
We had a falls view room which had to be booked directly with the hotel as that category doesn't show up on line. The room itself was not overly spacious at 30 sq.m. and felt a little bit cramped at times. But it was well enough appointed for our needs and I found the décor elegant in a country house way and pleasing. The bathroom had double vanities but only a shower (albeit a most capacious one with excellent water pressure). Amenities were of an unknown (to me) local brand which I enjoyed.
Food was very good throughout. Breakfast, which is included in all rates, was a lavish spread with plenty to interest the palate over several days. The buffet spreads at dinner were full of diverse and interesting items (truffled yam purée, anyone?) and rivalled the best we've encountered. A la carte dinner was perhaps a little limited in choices but every dish we ate was expertly prepared, attractively presented and well balanced. Poolside there were plenty of gap filling sandwiches and delightful "little plates" to tide one over between meals. Prices were unashamedly high but the quality did assuage the pain.
Service was slick for the most part. The doormen who stand around nattering all day and ignore guests arriving and leaving need retraining. They could learn from the friendly housekeeping staff and pretty much everyone else who provided very prompt, friendly service. The whole environment felt very welcoming and relaxed as a result.
The hotel doesn't have a concierge as such but uses an in-house tour operator. There are lots of complaints on line about how they push you into their expensive services when all you want is a taxi to the airport or whatever.* I don't know if that is still the case. I was happy to use them for transfers and our trip to the Argentinian side. (Door to door transfers are worth a premium price when you arrive at the airport at midnight after several hours of flying on multiple flights!) In our experience the services were flawlessly delivered and of a very high standard.
The grounds are beautifully maintained and the pool is large and well attended. Bird and mammal spotting opportunities add some excitement to the tranquillity of the vast and verdant landscaped areas.
All in all we were very happy with our stay and highly recommend this property.
* The logistics of access to the hotel are complicated. Only a few vehicles are permitted into the park so guests have two choices: use one of the reserved car services that will take you all the way to the hotel; or make your way by taxi or whatever other means to the park gate (the old one not the current visitor centre) where the hotel operates a reception facility and provides a shuttle service to the main hotel some 10 km away every 20 minutes.