NO!
I seriously believe that it's impossible to know another person COMPLETELY. You might know their reactions, behavioural features, their emotions, their responses and reactions.. you might even catch the nuances of their feelings and all. You can even predict and 'feel them' at that moment .. but, it's impossible to know anyone thoroughly. (it differs when you are talking about a lover and an acquaintance... with an acquaintance, you can easily guess what he thinks, etc. With a lover, the communication is on a totally deeper level.. )
First off, it takes a lot of effort, lot of time and awareness to know yourself, really as who you are. What happens generally is that most people arent true, sincere to themselves to begin with, and how can you even imagine knowing another person entirely?!
I'd say, it stops at 'feeling' another person's emotions. Besides, there is a mysterious beauty in not knowing another person entirely... and I like it that way ;)