The inspiration from Portal is unmistakable. I liked the dialogues with Dan - er, Entropy - very much. And the voice-overs were amusing.
My biggest gripe is that Sam's movement feels a bit sluggish and the physics are a bit ... challenged from time to time. When the boxes land on a button on an edge, it doesn't always register. Had to restart a couple of times because of this.
The mechanics are great. The time thingy makes for some clever puzzles with endless possibilities. A truly horrifying thought. :)
I wouldn't call it exactely an adventure, but it's a lot of fun. I enjoyed playing it. Good luck on finishing it!