The reason they seem to get to the crux of the issues so quickly, is because like most reality shows, it is heavily edited. A five or ten minute segment on the show reflects sometimes hours of questioning and discussion. From what I understand they have VERY long days (much longer than 8 hours, more like 12-14 hours a day) so it's almost an endurance thing for the sharks, because they spend so much time fleshing out the issues (and why wouldn't they since they're investing real money).
Personally I love the show also. Also check out Dragon's Den, which has both a Canadian and a British version (same format though, 5 investors all competing), and more recently CNBC's show The Profit where Marcus Lemonis (who was on the Secret Millionaire) by himself goes to failing businesses and invests a hundred K or two and takes over management for a week to turn things around.
I love this new era of entrepreneurship-themed TV, beats the hell out of Survivor or Lost. =)