I decided to go to Proyecto Asis based on reviews on this site and I'm sure glad I did. I went on the tour with Carlos and he is very knowledgeable, loves what he does and has a superb sense of humor. After the tour I did the volunteer part feeding the animals and that was such a feel good time. The highlight was cuddling the 3 month old cappuchin monkey while it tried to get me earring and glasses off. If you love animals and birds, this is a must do.
And it is super easy to get to on the local bus from La Fortuna. At the main bus station get on the bus marked CHACHAGUA, leaving at 7:15am. Get a brochure if possible for Proyecto Asis or tell the driver this is where you are going. It is near the town of Javillos. The bus dropped me right at the front gate at 8:00am and the tour started at 8:30...perfect.