I was pretty wary of how the glass box would look based on the original design - there are so many bad examples of ugly revitalizations of historic buildings where they tack on a big modern shape that is inconsistent with the original building (the ROM immediately comes to mind). But I think the (appearance of) separation between the addition and the original building in this case actually helps preserve a lot of the character of the old building. The glass facade is not too monolithic - it really doesn't attract a huge amount of attention and will allow passers by to focus on the original dent/pharm.
I'll reserve final judgement until it's fully complete, but I'm pleasantly relieved at this stage.