Just wanted to give some follow-up impressions before I move on for the night.
I put in a few hours, and most everything was good until I got to the very end of the session.
I'm afraid the game is going to be rather repetitive, which is kind of a shame because the beginning was totally hot. But it looks like the lion's share of the game is going to be Shootout in Jungle -> Walk a little -> Shootout in Jungle with the odd Shootout in Cave or Ruins thrown in. Being that these are all stop and pop shootouts, the excitement is a little, well, tame. There's also little variety in environments. The beginning of the game takes place in a central/south american jungle, the next part is in a pacific island. . .jungle. That looks identical to the first jungle. Basically, they are getting a lot of mileage out of those (excellent) jungle art assets, but really, two jungles in two different parts of the world are not going to look identical.
Anyway, the last 30 minutes of my session was shootout, walk forward a "room," shootout, walk, shootout. . .all in a jungle environment. And it got pretty not exciting fast.
But PS3 fans, give it a shot. I was never big on Gears of War, personally.