If you love working with animals, then this us the place or you. You get the sense that the first priority of those running it is for the animals.
About an hour south of Iquitos by collectivo (minibus) I would say it is well worth the journey, even if this is the only thing you can do in Iqutios. You learn so much more - about the animals, about the amazon and the culture - than you would on a tour.
Day to day you are expected to prepare meals for the animals, change water, clean eating areas, clean the manatee pool, prepare milk for the babys. The work is tough enough, nothing unbearable, but the heat and the mosquitos mean it's not a project for the faint hearted.
Rooms and showers are basic, no air con but the rooms have a fan. There is a hammock area for down time between animals' meals/other work with a projector if you wanted to watch a film in the evening. The wifi is about as good as it gets for Iquitos (in fact better than hotels in the city). Food is prepared for you three times a day. They can cater for veggie/vegan and I always found it was pretty tasty.
Compared to other centres in the area I have been told about, RAREC is the only one which doesn't tend to open the doors for hoards of tourists to come and pet the animals. This is in order to protect from infection - manatees and baby monkeys are particularly susceptible. I was also told by someone else that it is the only centre in the area which actually works towards release of the animals. They are careful about the diets - ensuring they are all getting the correct nutrients - there is an onsite biologist and they consult with vets, dieticians etc whenever there is a query over an animal. The animals are regularly monitored and, as is the plan upon release of two of the manatees next month they continue to monitor them and also track them to gather information for research.
While I was there there were also some biology students from the university of Iquitos doing a placement, which was great as it also meant you could practice your Spanish while working with them, if that's something you'd like to do.
I can't recommend this place highly enough, if you're willing to sweat through most of the day and forgo a hot shower then it is well worth it. I am so grateful to John and Ingrid for having me there and teaching me so much during my time.