Nervous tics and behavioral quirks aside, manipulating geopolitical events in Africa to frame Superman, using innocent victims as pawns and discarding them like trash, masterminding the bombing of the United States capital, praying on Bruce Wayne's inherent PSTD to manipulate him to try and take out Superman, kidnapping and torturing Martha Kent to try to force Superman to fight Batman,and then ultimately recreating a Kryptonian death monster that suceeds in killing Superman, not to mention other crimes to facilitate all of this...i'd say that's actually pretty damn dark and serious.
Yeah Eisenberg's Lex didn't look and sound like our mental picture of what comic book Lex is "supposed to be"...but his deeds? That's pure Lex. Moreso than most of the other live action versions. Again, Spacey and Hackman we're perfect physically, but the Lex Luthor they potrayed was farther from classic Lex in deeds and motivations than Eisenberg.
That's why I'm keeping an open mind about Cryer. Or at least trying to.