Was Ninja Gaiden hard, or am I just really bad at games?

There's no denying that video games of the late 80s and early 90s on the whole were much more difficult than they are today. It may just be because I was young at the time, or maybe I'm just bad at games, but there are titles in my NES library that I STILL haven't beaten. Not because I haven't had time to beat them, but because I can't beat them. They are just too hard....too hard without a Game Genie. Ninja  Gaiden is one of those games.