I enjoyed his talk because we share many of the same values and ideas: work relatively few hours per week but make them count, invest in your own future, etc.
For much of my career I worked at a large corporation (SAIC) but usually just worked 32 hours per week (anything above 30 hours qualified me for full benefits). For giving up 20% of my pay for not working Mondays, I had time to write, spend more time with family and friends, and simply enjoyed life more. David's company uses a 32 hour work week and he said that they have not lost productivity.
I also liked what he said about figuring out what things really make a difference to society and your career and work hard on those rather than spending too much effort on things that don't matter very much. Good advice, but not so easy to do. I live in a beautiful but remote area so my current career is basically competing with other telecommuters, many of them who live in countries with a much lower cost of living. Getting the most (important) work done in short time periods is crucial for my business so efficiency "is king" in my home office and as David points out, significantly more productive tools like Rails really do provide a good competitive advantage. I still like to build systems using Java server side technologies but only if I am certain that a customer can afford larger development costs and the project needs the extra runtime performance and scalability.
David also talked about life outside of technology and I am fairly good at taking time off for hiking, kayaking, cooking, movies, etc. That said, maintaining life outside of technology is a challenge for me because even though I can usually keep my consulting workload between 15 and 25 hours a week, I also enjoy writing (a lot!) and it is not so easy to limit my time. A little off topic, but one of the things that I enjoy most about writing is that the process always makes me understand things better. Often I will feel like I understand something just because I use it in my work, only to discover that in trying to explain something I realize that there are gaps in my own knowledge or my level of understanding is not as deep as I thought until I spend extra effort.