I find that in this day and age I'm always really impressed when I come across someone who is good at debating, refuting points and building up advanced and insightful arguments without making the too hard to comprehend for someone not as well versed on the subject, it truly is a rarity.
The world is full of people who think they are good at this though...
I think that's one of the main attractions in the opposite sex with me, being able to answer and being able to answer well. These people often have a great sense of humor as well.