Will you replace Facebook email with your current email service provider? Can Facebook give a tough time to Gmail and Yahoo?

Facebook plans to launch its new product, Facebook Email. With 500 million users even if Facebook manages to scoop a slight chunk, it will be a dominant player in the email service provider arena. However Gmail, Yahoo Mail and Hotmail will be tough rivals. Gmail is a superb email services as compared to the rest and prominentlystands out.
Besides this Facebook faces a certain drawback as it is banned in several corporates as a time waster. So Facebook has a definite ‘non-serious’ tag attached to it which might hinder users for using Facebook as a primary email service. One factor that can provide Facebook an edge could be IMAP and POP3 features to make it integrable with existing email providers.
What are your thoughts on this? What do you predict for Facebook Email and are you willing to use it as your primary email service?