bling, yeah. The physics are designed by a company called Havok, and in addition to being frighteningly realistic, they actually play a large part in the puzzles. You'll have puzzles in which you have a wooden plank and a barrel as its fulcrum, and you must stack heavy stuff you can find to balance the plank so you can climb up it.
The gravity gun is something else, too. You can just shoot stuff with it, as in it fires a lightning bolt that sends practically everything flying, or you can be more precise by alternate fire, which draws stuff to you and suspends it in the air until you fire again, which launches it through the air. I find that this alternate method is particularly useful, especially when there's stuff like explosive barrels or circular saw blades lying around