It's not the comparison, but the outright artistic reproduction of Apple's trade-dress. The commercial itself. White background, characters representing products, background music, etc.

They'd have a copyright case with regards to the production of the commercial, not the comparative claims made in it.

Parodies and satire are protected in the US as part of free speech, to among other things, be able to make political commentary. This commercial wouldn't, as far as I'm aware, fall under any such protections.

To me, it's just another "me too" commercial and IMO, looks extremely unprofessional and un-competetive for T-Mobile to have to rip off one of the most recognized and best performing ad series of the past decade. T-Mobile is a nobody in US telecom, somewhere between last place and completely off the map. It's great that they love the iPhone and want to stick it to ATT, but they could have come up with an original concept to do so.

I'm surprised they didn't rip off the Old Spice "Look and me, now look at your man" series.