Some plants are beautiful and it showed that these are the plants that would do well under such conditions. Some other inappropriate plants are already showing signs of decline and deterioration.
One stark thing that I noticed that is different from other rooftop gardens, is the lack of trees. I suppose the developer and management do not want to be burdened with tree management on the rooftop, which is definitely more complex and require more specialized arboriculture contractors, or the rooftop may not have been constructed to take the load of the bigger trees.