I've had two dinners at Vertical: one was a 5*, the other a 3*. The first one may not be representative since it was a dinner for food bloggers: it was served as a multi-course chef's menu, and each course was spectacular. At the second one, the food was still very good, but I had reserved for the dining room (with business guests) and they switched us to the lounge at the last minute since they claim that the entire restaurant had been reserved for a private party -- surely something that they knew several days in advance. This made for a less comfortable and professional dinner environment, although the menu is the same. I had a fish dish, which was well prepared, and a dessert that was good but not memorable, since I can't even remember what is was a week later.
The terrace is lovely, but you might want to skip the after-work crowd unless you like suits and smokers.