I got a chance to play the entire demo of Metal Gear Solid: Twin Snakes right away. The demo is only as long as a handful of cinematics and dialogue, and getting past about a half-dozen guards over two areas.

In terms of control, it feels almost exactly like MGS2. The R button will swap weapons, Z goes to first-person, and A can be used to beat up on enemies, or sneak up and put them in a strangle hold. X switches to crouch or crawl. I was very happy to be able to knock on walls and lure the enemies around. The control feels very sensitive, though. The player can look and turn VERY quickly, and the game requires a very slight touch on the stick to sneak around.

The E3 demo, although very short, also feels slightly tougher than a normal-difficulty game of MGS2. The guards seem to be able to detect Snake easily, and they can definitely end your life in a hurry. There's a chance this is a demonstration of 'hard' difficulty, or that I just suck at it.

Graphically, MGS:TS keeps up just fine. Some of the textures are still fairly rough, but there is also a very nifty effect where snow falls onto the camera (in first-person view) and melts after a second. The final version should be expected to look even better. Also, all of the cinematics are real-time. When fighting enemies, the camera automatically shifted to some very comfortable angles, which was nice.

The bottom line is, we're not being shown a whole lot, but what we're seeing so far is excellent.