It initially seemed out of place with what the rest of Trek had done in the past, in that usually encounters taking place would be so serious and formal.
But I liked it because it felt more real. For instance, if I was an evil renegade, I wouldn't care what I said or what anyone else, least of all my enemy, thought of me. I would say whatever I felt like saying.
Hell, if I was a Captain of a Starship, I would most likely begin the majority of my greetings like that, especially if I don't answer to the person to whom I'm addressing.