To those complaining that it will not hold onto a t-shirt, why clip it where gravity is against it, when you can clip it onto your shorts where gravity is helping to keep it cliped on? Anyway, it will stay on a t-shirt while running, unless you are a sprinter, and your t-shirts do not have seams.
I just got mine, the clip is fine and the thing is smaller than I imagined
I'm clipping mine to my Tshirt at the neck, that way gravity isnt pulling against the clip, and it'll be quite secure for running.
What would be nice is shorter headphone cable - with it at my neck I only need about 8" of cable !