the Worst
This hotel sucks. Although the younger staff at the concierge and front desk are often well-intentioned, management here is completely out of touch with their guests needs. Do not stay here unless you enjoy incompetence. 
Among the things they screwed up, many with management's oversights are: a simple flower order (After several attempts to have the concierge handle it, I ended up taking care of the order myself); communications (when they could not reach me by phone, no one thought to send me an email to the address they had used to confirm my reservation); parking (they assigned my car to another guest); and billing (my statement was incorrect, and because I was checking out on a weekend, no one could correct it until Monday morning ... I dont understand the logic, but I assume GM Carmucci does). 
The hotel is built cheaply, and the walls feel like cardboard. 
If you are a Starwood Preferred Guest, I recommend you stay at La Joule instead. As a Platinum+ SPG Member, I can assure you the W Dallas by far the the worst W experience to be had.