I recently went to the T Mobile arena for the Katy Perry Concert and it was a great show. My main complaints for the arena are the seats and traffic flowing in.
The aisles for seating are too small. Every time someone needs to leave the aisle everyone in the aisle needs to get up to let the person out. And if you happen to have a person in your row that frequents the restroom then your gonna be getting up a lot, which happened to us.
As for traffic, it's a nightmare if you're impatient. I'm not sure how they're going to improve this but having only 1-2 lanes flowing into parking lots is not good. It took us an hour just to park. I recommend taking an Uber or Lyft.