Broke immediately, support ignored me for weeks.
I got one when it firs came out in the US. I really like it, except that it sometimes comes loose (unclipped). I always noticed this, but always waited for the time that I *don't* notice it.
The odd thing is that it fits fine (I used the sizing guide), and it comes undone during mundane things like carrying food into the house. No problems when running etc though.
Mine died after 20 days. It won't charge, but boots up when plugged in. I went through the support links on the Nike website and received an auto reply that I'd hear back in 12 hours. After about ten days of no response, I started emailing Nike in the UK and US about 6 times or so. 3-4 days later, still nothing.
I posted on the Nike+ Facebook page asking why their new flagship toy broke right away during normal use, and I was being ignored by support.
Got an email 15 minutes later about my case. Funny that.
Anyway, still broken. I need to sent it in.