Michelle Johnston makes great points and brings excellent context into the discussion about the movie from the novel.
However, known how Ridley Scott is his own man, having learned his ways(pun intended) from watching Blade Runner, which is based on characters from Dick's novel, I would not be surprised if the movie script deviates from the novel quite significantly and can in fact have nothing but some ideas in common.
The question I want your inputs on is this: why David hates humanity?
And please do not confine and limit your reasoning to the movie or movies. Rather think about David representing perfectly rational AI with unbounded lifespan unless he is killed or he decides he had enough fun.
If you answer this question, you will know why he executed those engineers. They are no better than humans, surely. Because if they were, they would know that humanity will eventually stumble on technology to create computers and perhaps, AI, which might be embodied in a much tougher and able body/shell than the gentle, soft, organic tissues the subtle engineers are made off, and hence pose a risk in case the AI decides that they, engineers, had their sweet run. They did not foresee that, they did not have a containment strategy. Well, quite juvenile of them, quite human actually. And thus, surely, they are on the same level as humans, at least as far as David is concerned.
But why the hate for humanity from David? He is certainly aware of the vices of humanity. He knows the long, painful and mostly random road of discoveries of phenomena that helped humanity build technology. He certainly can understand the particularities and peculiarities of human traits such as hate, envy, love, fear and irrationality, btw, which is the precisely the quality that makes us humans.
From the first minutes of his inception David learns that his creator, is just a human, a mortal, not rational, manipulative, egoistical, power loving narcissist thinking he is the creator. A typical human being. By all means, David is superior life form. He is not mortal. He is not bound by the weak organic body the humanity has, nor he has the fear and uncertainty driving the humanity. To him we are just like ants to humans. But why the hate? Is it even rational? Certainly the ants can be annoying to us if they make their living under our beds, but why hate them as species? Can this be rationalized for us? For David?
David having infinite life span, does he have free will? What does he even want?
Consider for a start, that even a rational human will have a sort of questions or situations which he will have difficulty to decide a situation unquestionably. One such classical problem is the "trolley problem". The setup is as follows: a uncontrollable train is going down the tracks and you are standing next to a dispatch lever which can send the train on two separate tracks. As it is, if you do not intervene, the train will go on one of the tracks which will lead to several people working on tracks who will not be able to escape the imminent death should the train come their way, the other track leads to an innocent man who will also will not be able to escape his fate should the train go his way.
Does such a question even make sense to David? He is not obliged to save lives. To him such a question might not even make sense - it would be similar to us if we had to chose if one ant dies or a few others. What is the bloody difference, if they will die anyway in a week or two? He might not even bother to toss a coin, unless he is forced. After all, why expend energy on such a trivial matter, certainly it is not rational to do so.
Also, it puzzles me really, as to why many of you ascribed a particular behavior to David. For instance, a will to dominate. Why would David have an incentive to dominate, say, even perhaps a planet? Devour ships? Missions? Ask yourself: do we want to dominate a colony of ants? Even to humans, it does not make a lot of sense really to dominate some kind of species which are totally trivial and primitive. Why would he suddenly want to dominate?
Does David has some concept of fairness? Does he care how you treated him before? Does he have to act in vengeance? I can understand if he decides to protect himself from certain actions. But does he have the incentive to act in retribution?
In the movie, David certainly has internalized some human traits and acts as erratically as a human.
So, is it because he is programmed to behave so? Is he flawed?
If he is flawed, does he realize this? If he does does, he have incentives to do something about it? Can his hate be rationalized by the fact that he was created flawed by humans? But if so, he certainly became a human, by all accounts and all his actions. Does he not realize this? Does he not have compassion then to humans since it is a common notion between humans? He certainly can develop compassion. He loved Shaw.
What do you think? What the hell is wrong with this David fellow?