I love this movie. The characters come alive and I actually feel an emotional connection to them, and I don't usually feel an emotional connection to humans in movies. There are many themes/lessons you can take from this movie.
The one lesson I want to take away from this movie is:
I never want to be so focused on my "mission", my life, that I don't see that which is most important in life...people, relationships.
Eve was so focused on accomplishing her task, her directive, her mission. And she oversaw Wall-e in the beginning. But as time goes on, she warms up to his unique personality. And although Eve shuts down when she sees the plant, becuase her "directive" is accomplished, Wall-e still takes care of her, provides for her, and makes sure nothing happens to her.
Think of what Eve would have missed out on if she had never realized what was right in front of her face.