Manual reversion on the 737 is more than just the equivalent of losing power steering on a car, though that is a good analogy. It's a major emergency, and the impression I always had was it was a situation where survival is certainly not assumed. I am physically strong, but it would wear me out. It takes 2 pilots co-ordinated on the controls. Any sort of natural 'feel' is completely absent, and following a planned flight path is extremely difficult. The controls are VERY, VERY heavy and feel completely dead. The obvious critical time is contacting the ground, and flaring and any power changes make it a nightmare scenario. I find it hard to describe (apart from 'damn difficult'). The loss of the yaw damper is a triffle that one would hardly notice in comparison! It's the one feature of the 737 I never missed going onto something bigger with a nice round number of engines (4). If you ended up on manual reversion on that, your day was spoilt- there is not even any manual reversion!