This is with regards to the film by Steven Speilberg, just to clarify.
Many of the current reviews of A.I. spring mainly from the dichotomy between the film styles of Speilberg and Stanley Kubrik. Which are certainly there, but if you go into this movie looking for style, you're really missing the point.
The story which inspired the movie was a short by Brian Aldiss. The movie obviously plays out of the same mentality as Isaac Asimov's robot stories (if you haven't read these, do so, they're brilliant...and instructional).
There are a number of clear and obvious themes going on in the movie which are very necessary to think about.
From here on out, there's likely to be spoilage occuring, so if you haven't seen the movie yet, don't read on from here.
First off, the movie happens from the point of view of the robots. And these are robots who are programmed by humanity to do very specific things, and serve very definite purposes.
In an age where available land cover is very small, and humanity is fairly shrunken in population and birth is regulated, robots are used to fill in the gaps...whether for administration, labor, sex, entertainment, or what have you.
The main character of the film, David, is a robot created to look almost perfectly like a little boy, and programed to serve and to love his mother.
Not, mind you, to be particularly good at anything, or particularly interested in anything...aside from loving his mother.
Garbage In, Garbage Out.
Love is never truly defined in the movie. William Hurt's character seems to believe that it's a total state of focus and devotion, something of an extreme nature that should drive the lover to do extreme things to retain the love of the lovee.
There are a lot of complaints going around about how you can't get into David's head, you can't really get at his motivations, you really don't know what he's thinking. But that's nonsense, you know exactly what he's thinking...what he was programmed to think. He loves his mother, and he'll do anything to retain that love. Including crossing the world to find the blue faerie and be made real.
David cannot discern the difference between fiction and reality. He is willing to take any data which supports his focus - loving his parent - and make use of it in his quest. Even when he is told point-blank by his supporters that what he is chasing does not exist.
William Hurt's character would seem to define this as a dream, a passion, that he is following...but it is obviously, instead, an obsession...a directive. He is carrying out his programming.
A.I. focuses a great deal on the nature of the robots, of the awareness created in them of the world around them and what it was about...the hatred of the robots, even as they helped...when Joe's one lover was killed, and he ran, it was because unlikely as it was that he would kill a human, nobody was going to believe his word over a human's.
Our actual greatest viewpoint on the nature of the robots and their awareness was through Teddy, who was profoundly more aware of what was going on than David, or perhaps, at times, than even Joe. Teddy had been used and then put away...and then brought out again to accompany another robot, who though much more advanced, was somehow even more limited in function than himself. And so he becomes forced, in some manner, to become the parent, the conscience. David's Jimmy the Cricket, if you will.
It is even partially arguable, regarding the nature of the film and it's many changes of perspective, that some or all of the film is actually being related to us by the A.I.'s in man's future, who are telling it to other A.I.'s, to try to make them understand the nature of the vanished creators. The A.I.'s of the far future do not truly understand humans...but perhaps relate to them far better than they could ever imagine. They're concerned with where they come from, the nature of their creators, their intentions...they even model human form, roughly. They're still carrying out their programming...