The Pebble Steel has an asymmetric bezel, which makes some of the best watchfaces appear off-center and accentuate the limitations of the device. By taking into account the physical build of the watch, Zen for Steel appears perfectly centered and symmetrical on the glass face.
The weekday at the top of the watchface balances equally with the Pebble logo at the bottom. The typeface used is Raleway which is geometrically similar to the Pebble logo. So much so, I assume the logo is just a modified version of it.
If you want to make a similar watchface, here's a template I made and here's my source code.
