Oh yes, this is their worst nightmare.
He's logical, articulate, number-savvy, confident and likeable. Juxtapose Ryan with Obama, who comes off as a mean, snarky, over-exposed, jive-spewing economic bumbler.
Ryan will attract women, Catholics, and family-oriented voters. His young and attractive family, side by side with Romney's close family and grandchildren, present a Camelot-like picture. This provides a great visual for Americans who are worried about their childrens' futures, in light of the economic destruction Obama has wrought, and will persuade them that Romney and Ryan have every reason to share their concerns. This will hobble the left's efforts to portray Romney as an out-of-touch elitist.
When Bush picked Cheney, he left the Republicans without a future candidate. Romney's choice gives the Republicans ongoing leadership. Romney misspoke when introducing Ryan as the next president of the United States, but as a gaffe, it may well prove advantageous.