Each had its own advantages and disadvantages. Many will argue that portal 2's puzzles were easier. That's only half true. So far in my playthrough of the sequel, I haven't encountered the most annoying part of the first game: Those things that shot a little yellow ball that you had to guide to a receptor. You know what I mean. There were lots of em in the companion cube level, and the balls ricocheted everywhere. Those things made the puzzles difficult--cheap, really--, and I'm glad they removed them from portal 2.
Lizmichi said:
I love them both but Portal 2 is far better. While the puzzles are easier they're more complex them Portal Classic was.
This is pretty much my point. In the first game, puzzles were difficult only when they were slightly unfair. It was less of sorting through a complex puzzle, it was more of "Put everything in just the right place, bounce x around just right, and you win."
On the flipside, I was able to figure things out faster in portal 2. Maybe that's just because only now have I really got my head around the spacial reasoning and concept of the portals.
What about coop, though? I find the puzzles in coop more tricky.