Gosh, I missed this thread. DH and I did this the first year they added the Insider tours -- we did this one, the Roller Coaster (back when it was all coasters in one tour), and the wolf one. I really thought I posted here about them at some point -- but gonna search the forums so I don't repeat myself, and of course my info is several years old now.
In short, though, Animals Up Close is really good if you like animals OR if you want a quieter "down time" type of experience, or if you are curious about some of the overnight housing for the animals.
ETA: Ok, found it -- here's what I wrote in a thread about all the Tours:
The Animals Up Close tour occurs back in the wild animal housing area. You get to walk through and see the bird cages, the sloth's cage, etc. You also spend a lot of time in this small outdoor presentation area back there, and they bring some animals out one at a time, with various levels of interaction, from getting to let one of the parrots perch on you for a picture to some supervised petting of the more docile animals. We had some of the parrots as I mentioned, the wallaroo, the sloth was cranky so they didn't get him/her out, etc. The animals are the smaller, more docile ones that they also take to school programs and the like.
My information is a bit dated now, though, as I did these tours the first year they were introduced, in 2009. Maybe some others can chime in with other observations and details.
I think they definitely give you a great behind-the-scenes look and if the topic of a particular tour interests you I don't think you would regret doing one, provided you have plenty of time to take in all the regular attractions you want to see as well.
The Wolf tour is less "up close," for obvious reasons; you stay in the area where the wolf/predators show is given, get information about the wolves' training and care routines, and then get the chance to give a wolf one cue/command.