I would say he's been misused. Lex is to Superman what Joker is to Batman.
Give him proper treatment, make him a genius scientist/politician/philanthropist and let him be the feature villain in the next film. Of course he could have some help from secondary villains (Metallo?), but you NEED to take on the kryptonian alien vs human arc at least once rather then just introducing a bunch of super powered aliens.
And there has only really been one characterization of Lex in film... Gene Hackman and Kevin Spacey played pretty much the same characters in the Donnerverse and SR films. I don't want some dumb real estate scheme. I want a powerful and menacing Lex Luthor who has government influence and the people's trust.
Agree that he's been misused. There's a good storyline for a movie where Lex meets Superman, get's his "join me, together we will rule..." offer declined, and decides to develop things to compete with superman (something like Team Luthor, other weaponry). In the meantime, Superman knows Lex is a bad guy but can't pin any criminal activity to him. People around Superman questioning him for going after Lex and shaking his confidence in what he believes etc... Yeah if done right, there could be good stuff there.
But the movies have still had way too much Lex in them. I hope we can get a good couple movies without him, really. There are other major villains to be explored. Also, Lex is a "behind the scenes" villain, which leads to incredibly unexciting fights with his human henchmen or robots. If he's built up as a behind-the-scenes villain for a movie or two before being the main focus I think it'd work much better to show Lex's journey and reset audience expectations for the character.