I absolutely love the concept and I really hope that it works for the developers, and consequently lead to more being built in cities around the world.
When talking about conservation in any part of the world, habitat loss is always a serious issue. Equally, we currently have a rising population and need housing. Normally these situations are directly opposed, but if city “brownfield” sites are converted into tree-covered housing (and potentially offices) then this could be a fantastic net benefit. Adding the insulating properties of the plants, and the potential impact of pollution they could be a geniuine benefit to the health of the humans living and working around them too.