I tried several strapless bras (including from my favorite bra line, Fantasie) but none were as good as this one.  It's not like I'm going to be doing cartwheels while wearing it (and I can't do them anyway) but I did try dancing in it and moving my arms around, sitting, standing, walking and the bra didn't shift and everyone stayed where they belong.  It's not exactly pretty, but it isn't hideous either and as long as it does the job, that's OK with me.