I have been staying here for work for the last couple of weeks and this is a nice place. The rooms are large and quiet, however a walk in shower would be a great additional feature. Who doesn't hate taking a shower in a bathtub!
I was able to stay as an Platinum Elite guest and have access to the complimentary lounge on the 12th floor. You need a elite key to access the 12th floor and the lounge. The lounge is pretty large with televisions, newspapers, free drinks along with daily breakfast, some hot entrees at dinner and deserts. The hostess for the lounge works split shifts so she is there for 6am breakfast and 5:30pm dinner to great you with a welcome and a smile.
The hotel staff was very friendly and helpful whenever I needed assistance. The Hotel itself is located across the street from the downtown amphitheater so it is a good spot to stay if your in town for a event or concert. I haven't seen or done much in Phoenix but the Marriott seems like a pretty solid option for a stay.