Justin Trudeau

Pro:

• He appears to have won a tough nomination fight for the Montreal riding of Papineau back in 2007, and won the competitive seat held by a Bloc Quebecois incumbent (though historically a Liberal held seat) during a pretty bad election for Liberals in 2008, and subsequently survived the 2011 Liberal implosion.
• He backed longshot Gerard Kennedy, a pretty decent liberal, in the 2006 Liberal leadership race rather than the "safe" frontrunners of either Ignatieff or Rae.
• He has dual bachelors degrees from Canadian public Universities and has worked as a teacher, in both private and public schools.  
• I understand he's fluently bilingual
• It's not the biggest deal in the world, but facing down a stockier and younger opponent (and winning) shows some kind of mettle.
• He's not the US/UK Ivy league educated and former Goldman Sachs profiteer technocratic saviour that the remaining Liberal elites seem to be desperately courting, Stephen Harper's pick for Bank of Canada Governor: Mark Carney.
• I wouldn't put much stock in a flash poll finding that he'd win a federal election as Liberal leader, but it's of course good to start out as known brand that Harper's ad shop will have a difficult time defining negatively.

Con:

• It's undeniable we would not be talking about him as Liberal leader seriously if he was not his father's son.  Yes he is charismatic and so on, but it's difficult to imagine people would be half as aware of his charisma if he didn't have a famous name.  There probably are back-bench MPs who are charismatic but don't have that leg-up to household name recognition.
• What does he believe?  What kind of Liberal party would he lead?  What would his priorities be as Prime Minister?  His issues page is wafer thin.  He has my interest, and I take his support of Gerard Kennedy as a decent sign, but he has a ways to go to earn my support.
• At this point, it might be best for Canada that the Liberals pick a forgettable leader who leads them to a predicable 3rd place finish in the 2015 election.  There's a real danger of a giant NDP/Liberal vote split that keeps the Conservatives in power thanks to our antiquated first past the post voting system.  If you're a loyal party Liberal, you of course want the party to have the strongest candidate.  If you're a small-l liberal first, you want a progressive party in power and the more experienced Mulcair has to remain the more credible person to do that at this point.

Interesting/debatable:

• He conditionally endorsed the idea of a Liberal/NDP merger.  I'm disposed to be in favour of some kind of cooperation between these parties, and am glad he's at least open to it.  It also says something about his politics, as the Liberals who are against this tend to be the most conservative ones who still think liberalism is about repealing the Corn-Laws and letting invisible hands fix everything.  That said, I could be wrong, and it could be that a merged NDP-Liberal (NDP get top billing now as the bigger caucus) party pushes enough die hard NDP supporters Green, recent soft federalist Quebecois back to the BQ and blue Liberals to the Conservatives to still lose.  It has other potential downsides in the long term but I'm not going to give the topic a fuller treatment right now.

I'm going to need to read further on the Carney angle.  Right now my instinct is that keeping Canada out of the maw of the Vampire Squid is worth supporting a "legacy" pick who almost certainly cannot live up to his father's image and legacy (which are different from his father's actual record).  It could be an unfair impression but there are too many ugly signs on that book cover to ignore completely.