We'll start with the technological -- the suit can dash around quickly, allow Sam to perform crazy flips and stunts, and even speed up Sam's perception (which has the effect of slowing down the game's time). Additionally, while our demo had Sam wielding two different assault rifles, a shotgun, and two kinds of grenades, he only carries one weapon at a time, and that weapon just morphs into whatever you select on the screen. It's a fun effect, one of many in the game.
The suit is more designed for motion than for armor, so cover is a big mechanic in the game, just as in Gears of War. But once you figure out how it all works (there are different buttons for slowing down time, dashing, and jumping), Sam's suit is capable of some crazy stunts -- you can slide up on an enemy while shooting, slow down time as you approach, change your gun to hit him with a closeup shotgun blast, kickflip off of him, and then fling yourself behind cover as he explodes. The game's graphics can get crazy at times, with mechs rampaging in the background while Sam does his action thing on groups of Russian soldiers and robots.
The power suit has limits, of course -- there's a power core on Sam's back, and once it overheats, he can't use it again for a while. So you have to balance the shooter gameplay with the closeup action -- do you jump into the fray, or try to pick off enemies from a distance first? Explosive barrels are helpfully laid around the space station, and with some intelligent use of the surroundings, Sam can take on whole battalions by himself.
Later in the demo, I came upon a "pod walker," a large bipedal vehicle similar to the old AT-ST, and could kill the pilot and use it for myself (at least until it too exploded due to enemy fire). There were also turrets scattered around the battle in opportune places for blowing the enemy away.
Finally, after the room had been cleared out, a mechanical spider boss emerged from the floor, and Sam had to duck and cover while doing the usual spiel of aiming for the creature's joints and slowly whittling down its health bar. The creature was huge and spectacular, but the battle itself is an action game standby -- hit the weak points, hit the main body when you can, rinse and repeat.
If there's a problem with Vanquish (besides the oft-traveled action conventions, not that that's been a problem for Platinum in the past), it's that the game can be complicated. Sometimes, while trying to pull off a particularly cool acrobatic move, I found myself having to press both bumpers, move a stick, and hit a face button. And by the time I'd figured all of that out, I'd run out of power on the suit and had to slink back to cover for it to recharge. It'll take some training to use Sam's suit in the most awesome ways, and even then your fingers will probably get a workout.
But all indications are that it will be worth the reward -- Vanquish offers up crazy action safely embedded in some third-person shooter mechanics. We'll be playing more this week at E3, so stay tuned.