This is going to be a totally biased review since it is about the only WHS (to date) in my country.
Amongst its claim to being deserving of WHS status was that it is the only tropical botanical site and institution meeting the requisites for listing, which seems to be fair when a comparison is made with other tropical gardens. Its relatively young age might detract from its worthiness, though. That said, it is a pleasant, easy visit as it is a literal walk in the park, with modern amenities and public transportation within easy reach.