I am just constantly in wonder of how pathetic and weak-willed someone must be to have their enjoyment of a concert ruined by someone else in looking at their phone. I would think the ego stroking of getting to declare someone else "not a tr00 music fan" and yourself, by extension, better would be the sort of thing that would fuel many of your fragile self-esteems for another day.
I don't care if people look at their phone. I do, however, find it super distracting to watch a concert THROUGH someone's phone screen. I'm over it. I'm there to see the show and experience something, not watch the show through your fucking phone song after song after song. Put it down and watch the show. There's a difference between checking your phone to make sure your kids are ok and holding a phone up for more than 5 minutes....
I realize that makes me old, but I don't care.
I like checking my phone for texts and such; posting mostly short clips on instagram and facebook and sometimes twitter. Sometimes recording entire songs, if they are especially meaningful to me, and those sometimes go on Youtube to great general lack of interest (Except for a few which have a lot of views). Because I am virtuous, I try to stand to the side, near the wall near Food Food at 930 (come say hi!) and in similar spots at the other venues so as not to interfere too much with others' enjoyment of the shows.
The only phone use that bothers me a lot is the selfie video or pic taken with one's back to the band thing.