No. It is a mistake to think of it as "hello" and we want to discourage that mind set. nuqneH does not mean "hello" in Klingon society. It still means "What do you want?" For instance you should not use it when you walk up to a Klingon and want to be polite about your arrival. You also should not use it when you want to get a Klingon's attention because he is busy and does not seem to have noticed you (trust me, he did and he's ignoring you). The perfect time to use it is when a Klingon has walked up to you, but then just stares at you or seems to be evaluating you rather than stating his business. Then it is perfectly appropriate to say nuqneH "What do you want?" But that's a far cry from "hello".