The game is quite good and is about the same difficulty as Contra III. It is extremely nasty. I cannot get past level 1 on Normal. I've had to play the easy setting to progress. It has some similarity to Bionic Commando for NES in that you use some kind of arm extension to grapple.
If you own a DS, and not adverse to really challenging your gaming skills, I'd suggest you give it a shot. Worth the money IMO, and very nostalgic.