Ben's first word was "no." Oh, what a joy that was. It took a long time for him to say "yes" at all. However, in the end it was worth it. These days whenever I ask him if he wants to do X and he does, rather than simply saying, "Yes," he says, "Yea!" If I ask him if he wants to have juice or watch his favorite TV show not only does he say, "Yea!" but he also throws his arms up in victory.
Gotta love the enthusiasm.