There has been two videos released already of the game in the past couple of E3's. And surprisingly it looks, at least game play wise, fairly awesome. Check them out.
I'm looking forward to this. I haven't played MGS4 (no PS3), but I do know that Raiden was in that as some kind of super soldier with high cuban like heels. Still looks a bit of a twat.
But I am excited about Rising. I saw the video on XBL a few months back and it looks brilliant.
I bought MGS4 recently but haven't had time to get far enough through it to reach the part where Raiden enters. However I've seen his new look, and I've seen what he can do to a tank in the trailers, and it's pretty impressive. I think maybe Kojima realizes Raiden should have been the new Cyborg Ninja this entire time, rather than playing the role he played in MGS2.
The motion capture/animation mix in MGS4's cutscenes holds up very well after all this time (almost 3 years old now), probably making it some of the best of this generation. Raiden's appearance is one of the best of these.
I do suggest both of you play through the whole game when you can (or in your case Vincent should you ever get a PS3), the later stages of the game - while less open than the earlier ones - do get better than you'd expect, and one chapter in particular is awesome if you're a big fan of the earlier games.
Not the best game in the series but definitely should have been a worthy end to the series - if it wasn't for the fact they're still dragging it out (Peace Walker - which is actually very good, Rising and likely another MG title to be announced at E3 apparently).