My wife and are Marriott Platinum members and let's just say we stay at a lot of Marriott properties around the world. This hotel is new and very nice, situated very close to Chase Field and other main attractions.
The only reason this hotel is getting a 3 star review from us is strictly because of the poor valet parking situation. Marriott does not offer a self parking garage here at this location. This would normally be okay but when your valet workers are high school children with no drive/ hustle or customer service skills it becomes a problem. Upon arriving don't just sit in your car and wait for an employee to come get the door or offer to help you with bags, it wont happen!
I would have been okay with the lack of service had the parking prices been a little more reasonable for the hotel guests. Here's an idea Marriott, give your guests free parking that is included with your stay and then you can keep your half assed valet service.