Frankly I don't like this idea of Superboy prime as the villain - maybe I'm being a unidimensional fanboy here but I absolutely hated the fact that Superboy is now a villain. Of all the pantheons of Big Bads that are available in the universe why did they have to go with taking a "good guy" and turning him bad?
I understand how this is not the Superboy that I remember reading all those Smallville stories about and that Crisis on Infinite Earths changed it and all that. But still... Superboy is evil?!!
Because he was the only one locked up with Alex Luthor. Except Kal-L, whom they wanted to keep a good guy. I guess Superboy Prime didn't have to go as off the deep end as he did, but I liked it alright. I mean, for ten years, he was locked in a room with a guy just like him except better in every way--and who actually got to bring a woman with him, to boot! Going crazy's believable.
I haven't really followed what they've done with Superboy Prime since, but I understand it's been rather bad. "I'm going to kill you to death" and so on, which is either the worst line in comics history, or, possibly, the best.