More than what Lotus linked you to, vulnerability has a lot of merit.
Real vulnerability is men is found at your heart of hearts and it allows you connect the most easily and deeply with people. It's also something you must have if you want to pull the highest caliber women because they look for character in men which comes from your vulnerability as well.
So, it has it's merit in romance/love as well as seduction. Use it for what you will but keep that in mind as well.
-Richard