Nintendo Everything has just posted up 13 minutes worth of gameplay footage & an interview with a Sega rep that appears to have been recorded off the Gamespot live feed. It seems to be the first level of the game in which the player is exploring the abandoned (apparently) Sulaco. We see WY androids, Aliens, much of the previously mentioned large multi-platformed levels and the artwork:
In related news, the first preview of from Comic Con has also shown up online. Thanks to Ikarop.