Xperia Z Ultra GPe on T-Mobile

Hello, does anyone use the Z Ultra Google Play edition on T-Mobile? If so, how does it work on 4G and LTE? Any issues to be aware of?

I'm looking to buy one for my dad; he has a Note II, and wants to go bigger, as big as possible. He's fully aware of the size and how cumbersome it can be, but still wants one. For $450, seems like a good deal. Any thoughts?