A new patch has been released. This cleans up a number of small issues and defects, and hopefully improves gameplay experience.
Improvements include:
1) first person and 3rd person modes simplified with V toggle. first person forced in crouch spaces, ladders and combat,.
2) how forced crouched spaces work
3) backpack volume/weight management simplified and some bugs fixed
4) improvements to ladder climbing camera control
5) numerous little fixes and tweaks to levels