you can often get to know a person quite well from online as people are usually a lot more open. probably learning a lot about the person you wouldnt have found out otherwise. (if they're honest in the first place that is)
in my experience thats great and valuable but you dont really know a person until you've met them and spend time in their presence. theres a lot about a person you can learn just from how they look, speak, act, and move in the flesh.
its good to make friends online who you probably wouldnt have ever met otherwise, but from experience its not a good idea to go into meetings with other feelings beforehand. for example, a lot of people here think im quite nice, a lot think im a total dick. if they met me they might change their mind for better or worse!
my advice would be to meet him if you know hes been truthful and isnt some paedophile actor, but dont rush in.