I really like this bra.  I don't run but I use it for workouts, and I move around a lot.  It's comfortable and lets me move while keeping everything in place.

I only have 2 complaints - It's a little hard to get on and off; and I wish it had an absorbent panel in the cleavage area (sweat tends to build up there).  Other than that it is amazing.  I will be getting more of these.

Check the sizing info as given by the other reviewers... I wear a 34B and the medium is perfect for me.