I have the older version of this backpack
Deuter Race EXP Air 14+3 | Bike backpack
(A review of the backpack i have)
Its a great backpack. Its on the smaller side tho. It was big enough (when expanded) to have my kakis, button down shirt, shoes and breakfast and lunch but not much room left
The backpack was not water proof, but it does come with a water proof cover.
I no longer commute to work (moved to a not bike commuter friendly place), but I still use is as a day trip backpack (for theme parks for example).