My 11 year old is in year 6 and got an iPhone for her Christmas (slightly older model with good contract, unlimited texts etc but rose gold so she is over the moon!!)
Where we live is rural and it's a mixed bag how many of her friends have them!
She was absolutely over the moon to receive it but is very sensible and if ever takes anywhere makes sure it's zipped in a secure compartment in bag etc.
I have been quite sheltered with her and younger siblings but with her having to start getting a school bus for high school soon, wanting to do more things with friends I needed to grudgingly give her a bit more inpendence and the phone make me feel a bit better doing so.
I know lots of people will argue as kids we anever had them and survived but I do think it's one of these instances where times have moved on for the better, I remember a few times I really need to get in contact with my parents/was stuck when I was a teenager (including embarrassing getting my period on my way home) and a phone would have been a godsend!!...
The only thing I do keep an eye on is the constant posing for selfies and musically videos...but if it gets too much, I just take the phone off her and send her outside to climb a tree or something...which thankfully she is still really happy to do!!...
I think like anything it's just about managing it, and for us as long as we keep an eye on usage it's been really good move to make for her!!