I've run a couple hundred miles (not all at once!) with this armband and have been very happy with it. This is not my first armband -- I've used many others on hundreds of miles of runs and I'll tell you that all of them have their drawbacks. So far, this one is the best I've found.
A few notes:
1) The strap that comes with this thing is big enough to wrap around my thighs... both of them... while I'm wearing a wetsuit. You'll likely want to trim it up before heading out.
2) The locking mechanism can be difficult to engage. That said, it is very easy to get the phone into and out of the armband using the simple clip, but the mechanism that actually locks the phone in place can be a challenge to engage. Once engaged, I'm pretty sure there is not much short of a screwdriver or crowbar that will disengage the phone from the armband. I have found that most of my road runs do not require much more than the basic clipping. However, when I run on trails, I will take the extra time to engage the lock.
3) As others have mentioned, it is a bit bulky. I've gotten accustomed to the bulk and have chalked it up to the extra protection that I get both from the case and the armband itself.
(Posted on 10/28/13)