Here are some choice quotes from the Kotaku liveblog:

So stealth gameplay is confirmed to be in the game as well huh? Excellent! I like the swordplay action shown but I was keeping my fingers crossed that they wuld have stealth in there somewhere as well.

This may be a 18 rated game due to the cutting.

I guess this 100% confirms that the game has stealth, and will also be tied to the main storyline rather than merely being a spinoff.

Some fans have been wondering if Rising chucks the MGS series' trademark stealth. No, the developers said, there will be "stealth elements." But they said that it will be speedier stealth that utilizes Raiden's agility. Comparing the nimble Raiden to aging MGS hero Solid Snake, Kimura said, "so you don't have to worry about back problems like Snake had in the past." Kimura said he wants the stealth to involve heights, which sounded like he wants Raiden running on rooftops and such, though he did not specify.

Both seemed proud to be working on a Raiden game and explain this character's back-story. The adventure will bridge MGS2 and MGS4. (If you are wondering why they didn't mention MGS3, that's because that game takes place before MGS2 and 4). Rising will explain Raiden's drastic character transformation from solider to cybernetically-enhanced swordsman.

http://kotaku.com/5565967/metal-gear-solid-rising-bridges-three-games-explains-raidens-makeover