As it would have it, I also visited the Philadelphia Zoo for the first time last week, although I went on Tuesday. While I can see how the exhibits of the RSCC would leave some wanting for more, getting to see the great collection was definitely worth it for me: blue-eyed black lemur, Rodriguez flying fox, black-and-rufous elephant shrew, pied tamarin, red-capped mangabey, and of course North America's last red-shanked douc langur, Toi. I actually missed Toi in the morning, so I had to go back in the afternoon to see if she was out. Luckily, she was!
I was also successful in seeing my other must-see, the aye-ayes (which I failed to see at Cincinnati two years ago). I saw three of them, active during feeding time. Although it was quite dim, I was able to see pretty well and got even better views of them romping around and feeding than I thought I would. I had to give my eyes some time to adjust in order to see that well; most of the visitors that walked through did not stay long enough for that to happen, and ended up not being able to see aye-ayes that were right in front of them.
The Small Mammal House definitely needs more species. I wouldn't even say that it needs to be renovated per se; it just feels empty and rather forgotten. One entire wall has all of the windows covered up with wallpaper, which conveyed a sense of hopelessness for the building. I hope it's not just biding its time before closure, but that sure seems to be the case. Additionally, I did not like the aardvark enclosure at all, as it was all concrete with no digging opportunities.
The Reptile & Amphibian House was great. I counted up and it had ~60 species, which was less than I've been led to believe, but still nothing to sniff at. They had a pretty good repertoire as well: king cobra, Weber's sailfin lizard, black tree monitor, Hosmer's skink, dwarf crocodile (off-display as the female is nesting!), and splendid tree frog. I do wish they would replace the Nile croc and American alligator with small endangered crocs, but otherwise I really enjoyed it.
The rest of the zoo interested me less and most of what I saw species and exhibit wise just seemed okay. On the upside, I liked the McNeil Bird House and how most of the species in the walk-through aviary were visible, as that is not the case at every zoo (*cough* San Diego *cough*). The hornbill enclosure looked really small though. On the downside, Bird Alley is very underutilized at the moment, and the penguins lack water deep enough for submerging. Fortunately, the new digs they get soon should solve the problem.
While it is impressive and a great option for the animals, we didn't see any animals utilizing them other than in the new Water is Life exhibit.
Save for two barely visible squirrel monkeys sleeping in the Primate Building's entrance to the trail, I also did not see any animals utilizing them. Definitely a neat concept though.