I just found out about this game a few months ago myself. How did this sneak under everyone's radar back in the day!? It looks more like Bionic Commando, you're right. Not that its a bad thing... just a strange design choice.
I have never played the original Ninja Gaiden games. In fact, the only game I played in the series was Ninja Gaiden Sigma on PS3. That's something I've been meaning to rectify and this one looks like a fun Game Boy title to jump into. Nice review man!