I thought this game was pretty cool. Konami proves themselves as a worthy company once again. I recently beat it, and I had fun with it from beginning to end. The feature that I enjoyed the most would probably be the hostage situations, especially on the airport level. That was a very intense scene...dodging ninjas while saving hostages popping out of the aisles. I hope that Konami either makes a sequel or another game relevant to this one. As for the chain-grapple thing, was I the only one thinking of Castlevania? Especially the Castlevania for the SNES (I can't remember which one that is). Bionic Commando gave me some flashbacks as well when playing this game.
Anyways, I just hope that more side-scrollers like Ninja Cop get created for the GBA. IMO, I think that's what the GBA is all about. Some of the 3D games that have been released are good, but I think that game designers can work more with side-scrollers when it comes to the GBA.