The first chapter was nice in that I liked seeing the reworked levels, it was interesting to see how the designers rethought the very basic lessons about portals, however the voice over in the first section was really boring for me, we didn't get to know who that voice was, the jokes were fine but it felt kind of cold and out of the blue. But after that, being back with Glados doing the voice overs and the new puzzles I loved it, it was like a reunion, it's the most typical sequel-ish section and I liked that a lot.
The chapters directly after the supplanting were funny, and interesting to look at, but I didn't really like the early paint puzzles, however when we got to use them for the traversal I liked it more.