AFAIK, the proposed upgrade costs about the same as the normal difference between a standard and Executive floor room (don't know about during the sale). I have tended to pay for the Exec floor at this hotel as the cost of breakfast and internet alone just about justifies it. The Executive lounge on the top floor is quite nice, with decent selection of snacks and drinks. Breakfast downstairs in the restaurant is very standard but perfectly OK.
The hotel is connected to a decent shopping mall (discount/outlet type) with a good selection of food in the food court and a couple of good Chinese restaurants. The hotel is actually one of my favourites in Hong Kong.
As the above poster said, it'd be better to get it for free with A-Club status.