Anything above 50mm is good for upper body/headshot portraiture IMO. You don't get that iffy distortion like you would using a wide angle. For full body though, any lens can work, depending. But ... as mentioned, with longer focal lengths, you get that nice compression of the backdrop, which usually leads to more pleasing results, a less cluttered backdrop, better bokeh, an almost 3D 'pop' at times, separating your subject nicely from the backing.
I do like to use my 85mm for portraits, but also my 150mm - given enough space [though as that's a macro lens it works well even in smaller areas, for head shots]