Bionic Commando Rearmed is a pretty faithful remake to the
NES version of Bionic Commando. Run and gun gameplay in mostly vertical-scrolling stages? Check. Grappling gun? Check. Inability to jump and inability to shoot vertically/diagonally? Check. World map that gives a limited freedom on how you can proceed with your mission? Check. Communication centers? Check. Various weapons and items that you can find and use? Check.
There are differences, though. Aside the typical enhancements to graphics, soundtrack and physics, the game now allows you to fast-forward any dialog from the communication rooms and it autosaves between stages, so you no longer have to worry about doing it all in one sitting or leaving your game running. Other differences include
real time weapon change (rather than being limited to just 1 weapon/stage), more varied boss battles, rebalanced weapons (so the rocket launcher is no longer the ultimate weapon), some easier sections, a hacking minigame (seems to be standard those days) that reveals information about the stage's boss, starting with a healthbar from the beginning (and you can only upgrade it once) and enemies dropping health powerups upon death. While a bit easier, make no mistake; the game retains all the frustration-inducing platforming challenges of the original, so if you couldn't handle that one at all, you are advised to stay away.
As for things I didn't like, well, some of the new "humour" from the game's dialog made me cringe and the new last level proved to be a major pain in the ass, mostly on account of being too damn large. Lose all your lives and you'll have to start from the damn beginning.
Dammit, why did they have to make such a mess at the end? Urghhh...
Anyway, the complete list can be found
here.