I really like talks which are about sharing knowledge of the lessons somebody learned. Even though some projects you mentioned were before you used an Agile approach, it's still valuable information, because you learned from it. And you want to share it to prevent that somebody makes the same 'mistakes' you did.
Specifications, specifications, specifications. The power of repetition. Your message is clear.
I enjoyed the subtle jokes during your talk, keep them in your talk! I think everyone can appreciate a joke now and then. A good addition from the audience was managing expectations, which you could add to your talk.
This talk provides good pointers for dealing with different types of projects in different types of organizations, especially for freelancers. For the experienced developer this may be a talk that hits a lot of obvious points, for others this may be a good opportunity to learn from someone who's gone through the process numerous times. Either way it's fun to share these experiences and come up with good strategies.
The feedback I'd like to give is to make the slides more engaging which would also provide more structure to the story.