That warping is there to compensate for the warping of lenses, so in the end it looks (almost) ok. I think the compensation isn't optimal yet, but I think I have also an issue with the FOV there.
Immersion is better mainly because the stereoscopic view and the large FOV gives a great sense of scale. When you approach the truck and look at the tires, they are massive as they are in real life, which isn't really conveyed via a monitor.
Turning the head isn't the primary immersion factor actually. I mean, you will do it naturally when the immersion feeling is already there, but you can relatively easily get used to not turning the head and turn with the mouse instead. The latter is also a bit less nauseating, but I guess it's a matter of training.
The resolution is low, if you focus you can see the individual RGB stripes. But the brain gets used to it a bit later and starts filtering it - especially when you start to be captivated by the scale of things and the world.