Calacanis is right about this much: having a kid is not overrated. It's amazing. However, I would echo another commenter here and suggest that what I've observed is that I waste less time than I did before the baby. Over the past few weeks I've been more focused and "in the moment" when I am working, because I know once my allotted work time is over, it's baby and Mommy time and rightly so. I've also, in general, been suffering fools less gladly. My time is worth more now.
The one thing I would disagree with Jason about is waiting until a specific time (he says 30-something). I think it's a mistake to reduce it all to a matter of age; it really does depend on the personalities and circumstances of the parents. Some people are not going to have the energy at age 40 that they had when they were 20, especially if you didn't take care of your physical and mental health when you were young. He's right to add that they use up a lot of your energy. Another reason to consider starting a family early. I'll be 60 when my son turns 18 and presumably starts college. Not everyone wants to do that, or can!