I'm with lyte on the benefits of the Peace Walker scheme for newcomers. Three additions are third person aiming, crouch walking, and the ability to move and aim. It break the AI and design a bit, sort of like pointer controls in RE4 Wii. But it does make the game easier, if not dumbed down.
Realistically, for someone who'll never buy a non-Nintendo console, MGS3DS is the only option and it isn't that bad. It's the worst version of the game, but take away the more recent versions (HD and Vita) and compare it only with the PS2 game(s) and it's competent. There are problems like the dumb motion control additions like balancing on the bridge. Sometimes the ugliness hurts the gameplay because you can't discern between enemies and environment in the distance. And a bunch of technical problems; frame rate, audio, load times, etc.
CCPro helps but it's probably still playable without. You use the face buttons to aim and it has crazy amounts of auto-aim to compensate. Lots of commands are on the d-pad and touchscreen so there's that too.