I've been to this Starbucks many times to finish some work. The upstairs seating area is great - lots of seating and tables (and a decent amount of outlets). The stairs are somewhat hidden behind the checkout counter.
Like others have said, the lines here can be pretty long. But, this is to be expected with the store being located in the center of Playhouse Square. Also, this Starbucks' location means parking is a pain - you will likely have to park in a garage nearby.
There are 2 separate bathrooms here, one is located opposite the checkout counter while the other is tucked away in the very front of the store. It's a bit of a squeeze to get to this one as there is a high top table somewhat blocking the way.
My drinks have been decent in quality, and the staff members were friendly when I placed my orders.