I have created many word portraits in the past and have always limited myself for the sake of simplicity to completely horizontal or vertical words. My interest in word portraits has been re-ignited by a recent client project and I've started to play with allowing angled text.
In this first example below the words are flat when near the horizontal middle and gradually turn to vertical at the edges. I also swap the orientation below the vertical middle.
In the next example the angle of the word is determined by the brightness level at that point in the image. White regions are flat and dark are vertical. This gives a reasonable contoured effect because the brightness levels in the image vary in a natural fashion.
For this last one the words are all angled towards a point on one of Einstein's eyes.