The biggest change is the addition of the 3rd floor, which is meant to be a VIP floor for private appointments - it has a small bar, chairs and tables, and racks that would be prepared for the person who will have the appointment. There is a long table where I assume special bag offers may be made.
For the other two floors, which were always a part of the boutique since it originally opened at that location, they re-oriented the space and added a lot of different storage and display areas. They also redid the spiral stairs in a manner that opened the space. It feels more spacious but they did not add more square footage - that is, they did not expand into the store next door. They may have increased the floor space and decreased the “back room” space, but I don’t know for sure - it’s possible it looks bigger because of the way they reoriented the layout and added display areas. It certainly looks like more fits in the store and there is more inventory for men’s (now on the 1st floor) for sure. I’m not sure of the changing areas. I saw the VIP dressing room the night of the party, and during my appointment I tried on RTW in a dressing room on the 2nd floor, but I don’t know if that’s the only dressing room for use for the 1st and 2nd floor customers. The space does look quite different with lots of nice details.