Strong messages about the dangers of over-consumption and excessive waste; the vision of Earth as a garbage-strewn wasteland (and humans as hoverchair-bound lumps who can barely walk) speaks volumes. The importance of protecting the environment -- and the consequences of inaction and greed in the face of potential environmental catastrophe -- are a cornerstone to this movie. Other themes include loyalty, friendship, courage, perseverance, teamwork, and staying positive.
A human does battle against a robot, which pokes him in the eye and tosses him around, but it's not too aggressive. Robot EVE has a powerful gun in one of her arms, which she doesn't hesitate to fire at possible threats (including, early on, WALL-E). At one point, in frustration, she sets off a series of vivid explosions in old oil tankers that could scare some very little kids. A gang of rogue robots faces off against similarly mechanical peacekeepers; their conflict is more funny than scary. Human characters are briefly in peril.
Gentle, sweet, understated romance blooms for two robots, as well as for a human couple.
Excessive consumerism is one of the movie's themes. It's personified by the Buy N Large mega-corporation, which seems to own and operate everything in WALL-E's world. It's fictional, but its brand is everywhere. Also lots of tie-ins outside the movie for WALL-E merchandise, from toys to books and more.