Gotta tell ya, if some of my suspicions about what I saw from the demo on On the Spot are true, I may be withdrawing my preorder.  Some of these issues were:

1)  Extremely linear design - While the idea of portals and walking on ceilings is very cool, it won't be as exciting if it feels like the whole experience is on rails.

2)  No weight/momentum system - Some people may not know what I am talking about, but if you play the shooters that are out now and then go back to older shooters, you will hopefully notice something very important.  That being in older shooters, the player seems to be gliding or floating rather than walking.  That was one of my major issues with the Timeshift demo.

Hopefully I'm wrong about these, as even something this small can ruin a game.  Not saying the game still might not be good if it has these issues, just not great like I was expecting.