It was very good, I don't have lots of gripes with it. The Sixaxis parts weren't that wonderful, but then again they don't represent a big part of the gameplay. It does look really really good, and I like the style of the cutscenes and the premise. I was sorta nagged by the screen tearing and hope that it's fixed in the final build, but it wasn't that overwhelming. Can't wait to uncover more of that storyline. It reminds me of one of my favorite platformers of all time that everyone has forgotten now (Montezuma's Return), but with less platforming elements, and with the look and the story of an Hollywood blockbuster.
The gameplay so far in this short level does remind you a lot of Gears of War, but it feels more natural. It felt pretty exciting, and the combination of GOW shooting and jungle exploration feels strangely good. Drake is portrayed well, he isn't portrayed like a super hero and he's pretty distraught by what he's going through, and the animations along with the character's look reflect that. That makes him sympathetic, and you immediately identify yourself to him. It's thus cool to explore that mysterious place where dangerous baddies can pop out of the woods at any minute.
At some point the shooting parts and the enemies encountered began to get a bit repetitive, but this demo sounds like some early part of the game only, like a prelude to make you become more acquainted with the gameplay elements and warm you up before the real action begins. Based on what we've been shown the parts that are to follow will feature lots of variety, charismatic villains and sidekicks to meet, enigmas to solve, and some exciting stunts to do, Indiana Jones-style.
I can't understand why anyone would hate on this, it's a well-rounded product and it played like one of the best games of the year. It's got tons of potential, I don't care what's the name of the system that runs it, it's completely immaterial. Ultimately I think that either Bioshock, Assassin's Creed, Mass Effect of Super Mario Galaxy is going to win the GOTY award, and I'm hyped much more for Mass Effect as far as November releases go, but the demo made me very eager to the full game's release. I'm probably just going to rent it though since it's supposed to last for like 12 hours.