I mean, the background and setting of the story is video games, but surely when watching it, you won't be thinking, "OMG, I'm watching a 90-minute video game!" I mean, I'm sure we'll get absorbed into the story and care about the characters and all...!
The story (if I am not mistaken), is about how people are perceived to be evil based on looks or occupation. The plot of the Fix It Felix game is that they destroyed Ralph's home in order to make a building, so when Ralph tried to fight back, he was made the bad guy while the "good" guy was praised for his actions.
I doubt the film will get all philosophical about it, but it will talk about how sometimes we praise the wrong heroes. Someone already said that Felix could turn out to be the villain in the end, and quite frankly, I would LOVE to see it happen. Even if it's Pixar-ish, it would drive the plot to a different level.
Also, I keep hearing that this is ripping off Despicable Me and Megamind. I don't see it. The only similarity is that the focus is on a supposed "villain", but there are plenty of differences. In Despicable Me, Gru is a villain that enjoys being one, but learns about the importance of fatherhood. Megamind has fully accepted his villain status, but later learns that he could be something more. In Ralph, it seems that he admits to be a bad guy because it was the job he was given in his game world. It sounds to me like the story is learning to overcome prejudices and go outside your comfort zone if you want to make a change happen.