Unfortunately missing a tour of the interior, the main draw is obviously the building's sheltered plaza, seen above in the approach from the Main Street entrance. As my friends pointed out, the columns -- set at various angles in a manner resembling a project (PDF link, see page 4) by Zaha Hadid -- resemble tree trunks, a metaphor that will be strengthened when they are painted a dark brown.
The large asymmetrical canopy is designed to collect rainwater, to be used for gray water in toilets and for the pool in the left foreground of the above image. Materials inside and out (per a conversation with the Assistant Director of the Center) are geared towards achieving LEED Platinum status. For example, the horizontal wood slats overlooking the covered plaza are salvaged, as was the wood used to form the concrete volume visible in the last image.
In addition to the building's materiality and incorporation of sustainable processes, the Visitor's Center is integrated into the site via a green roof that slopes from the garden level to the top of the auditorium (to the right of the guardrails evident in the picture below). The building can be accessed from this upper level, allowing the garden to flow towards the Center and make for a fitting entry when the building is complete and the main entry to the Botanical Garden is reoriented.
Links:
:: Queens Botanical Garden
:: BKSK Architects
:: LEED
:: Green Drinks