Now designboom has an update showing the completed structure and it is impressive. They write (without capital letters, as is their wont):
the concrete waffle slab, ‘holedeck’ is a patented system of voided parts for buildings that have large spans between supports and a high level of services. it can be pierced all the way through, meaning that these necessary systems occupy the same amount of space as the structure itself, so that no additional suspended ceilings are required to hide them.
Waffle slabs are expensive, but use a lot less concrete than flat slabs in long spans, (a very good thing) and this is a really elegant integration of services into an attractive system that doesn't need to be covered up with a ceiling.
More at designboom
Alas, Toronto lost its best example of waffle slabs, at Terminal One in Pearson Airport by John B. Parkin. Waffles and salt don't go together.