We enjoyed the half-day we spent at the zoo, and certainly could have spent longer here, but we'd already done a lot of walking and needed to rest our legs! On that front, the free shuttles, which do a loop around the zoo, are much appreciated. There's a huge variety of animals to see. The walk-in butterfly and wildlife enclosure was the absolute highlight for us. Some of the exhibits are looking a little run-down, and most of the eateries were closed when we were there (a quiet Monday afternoon), but generally we had a lovely time.
Given the zoo is in the north of the island and not connected to the city by metro, we opted to get a Grab ride there and back to avoid the kerfuffle of navigating the public transport options. This added a fair bit to the cost, but was very convenient.