I was personally somewhat disappointed in how Lex went out. I know that he supposedly became "truly" evil in Descent, but even at the end of Arctic when he supposedly "destroys" Clark, he still had the "it's my job to save the world" mentality. I expected Lex to further develop his evil personailty to the tune of "eff the rest of the world...I'm going after what I want." This is the Lex Luthor we see portrayed later in the comics and in the movies.

So at what point in the show was Lex supposed to become "the greatest criminal mind of our time?"

I always felt that Lex had the whole "the road to hell is paved with good intentions" kinda thinking. He believes the ends justify the means, if that means killing 200 people to save 200,000, the so be it. ya know?

I think he did great....and I also feel that he'll be back here and there in season 8 to show all what he has done during his time away from Smallville.

I agree with iamtheonewhoisme. I think that Lex has always been portrayed as a person who gets what he wants by any means necessary and he thinks of himself but also of earth in a twisted way. By that I mean he wants to get rid of Superman because he has the potential to turn against humanity at anytime and rule everyone. So he wants to get rid of him. He thinks hes saving Earth from an alien invasion and yet he still has a personal vendetta against Supes as well. When I hear him say that he's doing it for the good of the planet, I think thats his twisted way of thinking he's not evil. Yet, he thinks if he was in control he could see to it that nobody messes with his planet. And if he had to kill a few to save a bunch then he'd do it with no hesitation. Thats how I've always seen Lex except in the movies so much.

Then explain in Superman Returns (for example) the scene where Lex is explaining his plan to Lois. He shows her the maps and explains that he intends to create an entire new continent, while drowning the USA.

Lois: "But millions of people will die."

Lex: "BILLIONS! Once again, the media underestimates me..."

That scene comes across to be pure unadulterated greed, with total disregard for the good of the people.

yeah, thats why I said its different in the movies.