The iPhone has a clearly-better user interface
When I broke up with an excessively-spammy girl, there were something like three hundred text messages from her clogging up my phone. I didn’t want to delete messages from other people, but my choices on the Nokia were either delete everything or delete individual messages. Very, very slowly.
So I got rid of the phone and got an iPhone instead. It was easier, and the Nokia was crashy and falling apart anyway. I’m unimpressed at Nokia’s recent efforts—and they used to make really good phones, too.
The most recent ex-girlfriend wasn’t nearly as verbose, but there was still communication from her clogging up the phone. However, on the iPhone, deleting all of the correspondence from a single person is a simple matter of going to the message index page, swiping your finger across their name, and hitting the “Delete” button that pops up.
The iPhone: for those times when you just need someone entirely out of your life.
Also, contacts→$EX→add field→Suffix is very useful to add a verb describing $EX. When my phone rings and it says “$EX lies constantly”, it very much lessens the temptation to talk to the liar.