But i became curious as an american , is there any documented history on how these German soldiers felt as they saw hundreds of landing craft on the horizon.

Plenty, if you know where to look; here are some accounts documented by Hastings in Overlord. This response will be far from exhaustive, but it will quote only two separate, but what I would deem typical, experiences. I want to focus your attention two central themes: One, confusion permeating through all ranks of the German defenders, in the former case culminating in orders and counterorders, and the inability or lack of will to give effective resistance. Secondly, the idea that numbers were furthest from junior soldiers and leaders minds; if they were retreating, it was because they were under intense pressure, out of ammo, or being ordered to do so.

Leutnant Rudolf Schaaf, commanding a self propelled battery 1716th Artillery was telephoned at 3.00AM and ordered to take his guns to join in a counterattack against the British airborne bridgehead. Yet he had driven only a few miles across country when he recieved a radio message recalling them to their original positions.

The confusion of the airborne drops, the expectation of a seaborne landing, coupled with being out of touch with higher headquarters, makes the first crucial hours of the D-Day invasion one of confusion and fear for the average German soldier.

Another quote illustrates what you suspect, and what I just iterated above, about the shock and spectacle of seeing an armada steaming towards your shore:

Many of the defenders of Utah Beach...were still helplessly stunned by the bombardment or demoralized by the spectacle before them as them as the first landing craft closed in. In strongpoint W5 [my note: 'W' is short-hand for the German word for 'resistance nest' - a concrete bunker in this case], at the very center of the seawall...the men of 3.Kompanie, 919.GrenadierRegiment had lain shaking, hands pressed to their ears...

Utah, unlike Omaha, went basically essentially as envisioned by the Allied planners; and the exits were secured rapidly and without great loss. Its fairly common knowledge that Omaha did not go as well; but the experiences there could be much the same. The difference is, resistance nests at Omaha, like W5, remained relatively unsurpressed, and were able to man their positions before the Landing craft (floundering in the channel) could drop. Utah and Omaha have the shared experience of units landing basically anywhere and in mixed order, but without the chaos of receiving artillery and machinegun fire.

we see a solider throw up

This could happen for more than reasons of just fear. I just wanted to point this out.Successive and extreme concussive force could nauseate a defender to the point of regurgitation. This would undoubtedly be excaberated by being in a closed space, like Resistance Nest 5, if accurate naval and air bombardment is coming down on you. If this helps build a picture for you of what an initial German defender may have been experiencing.