Well,how about by predicting some of the plot twists, shocks and effects that Kojima will inevitably weave into his last (huh, he's said that before) Metal Gear adventure. We've had a mindstorming session to size up the potential plot and gameplay madness, and this is what we came up with...
Note: This is pure educated speculation on our part, we've had no confirmation of any of these points from official sources.
No one will really understand the plot
In Metal Gear 'plot' generally equals 'metaphysical philosophical debate loosely linked by sneaky-sneaky shooty-shooty'. There's narrative, sure, as the player advances through each level or area. But Kojima's dialogue is shot through with mind-bending theories and scientific or military jargon, delivered more as social commentary than conversation.
Early on, MGS4 thrust the ideas of Private Military Companies and third generation genome soldiers into our poor minds. Now it's twisting these twists, as Liquid Ocelot (a twist in himself) triggers some soldier-gene assaulting migraine-machine that leaves Snake and co clutching at their noggins as if they might burst.
It says something when the supple (cynics would say 'vague') strands of Kojima's script can result inone trailer being interpretedas a metaphor for the console wars and MGS4's PS3 exclusivity. It says MGS4 is going to be full of super-complex and grey-matter bothering plot. One thing is certain - only Kojima will understand it all.