the ending is kinda a weird one for me. wish it would have ended differently.
It might have made more sense if the final scene had included action from the book, in which the "star-child" reaches out a finger (perhaps the finger was just a metaphor for some sort of thought-field) and detonates all the Earth-orbiting atomic weapons, one at a time.
Either (a) that was too much for Douglas Trumbull's special effects team to accomplish, or (b) Arthur Clarke added that detail to the accompanying book after the movie came out.