Right , this is a condensed summary of the features of Metal Gear Solid : Rising.... Come'on Kojima , we need MOAR SNAKE!
MTGS isn't right without Snake! How can Metal Gear Solid be SOLID without SOLID Snake!?

.... Then again , MTGS 3 was about the Big Boss and the PSP games are about him as well... *cough*

Anyways...

Essentially , I'm sure you all know by now , MTGS : Rising features a "cut and take" system. You slice the enemies up and they drop goodies for you to collect.
To put it bluntly , it's a bit like DMC or Dynasty Warriors. You bash the enemies up , they drop stuff for you to collect.
Such items can range from health to... well , information and parts.

As the trailers had shown , the player can enter a "slow motion" mode to slice the enemies into... well , bits , but it can also be used for strategical and tactical purposes - ranging from figuring out where to cut your enemies ( If their heavily armored ) or better still - deflecting bullets. ( Pew! Pew! Pew! )

Unlike most MTGS games , Rising does not feature the same sort of "stealth" which it have to offer. Unlike the previous installments of which Snake was essentially the mouse and the guards are the cats - the role is reversed.
It's a bit like those ninja games. Y'know , like Tenchu? You'd have to sneak up to your enemies and well , choose what you want to do with them.

There is another important factor of which is that killing humans does not offer any benefits to the player. Killing robots , yes , but not humans.
It is noted that there are rewards given to players whom had played through the game without killing any HUMAN BEINGS. Other than slicing people up , you can always knock them out.

So it's pretty obvious what the enemies in this game are - robots , humans and humanoids.

Oh , as a side-note , it is to be noted that Raiden may use weapons other than his katana. Though it isn't quite clear how many weapons is exactly usable in this game.

It is also to be noted that Rising would be less plot heavy as compared to the other MTGS series and it would have a heavier empahsis on the gameplay value.
But one way or the other - would you choose to butcher humans or spare them?

( I wonder if this is the end of MTGS? :X )