I've only played a handful of Valve titles and I think they're the best game developers in the industry (Orange Box and Portal 1/2). I'm sure this has become a cliche, but I see them as the Pixar of the games industry and it's quite clear they look to that company for inspiration (at least to me).
With that said, I haven't finished the game yet, I think I identify with the criticisms made by people such as Giolon and Yahtzee.
I think Portal 2 is more maze puzzle than logic puzzle. Someone smarter than me might be inclined to disagree, but logic puzzles, in my understanding, provide a challenge in the sense that; the solver's capacity to deduce a standard or general solution is threatened by numerous possible (wrong) solutions. The essence and enigma of a logic puzzle resides in that challenge.
Portal 2 doesn't seem to have that challenge. All elements within a room are deducible to only one logical order, making Portal 2 more of a Jigsaw or Maze, than a Rubix Cube. The former largely tests memorization, perseverance and focus, which are more LCD traits in humans. Once the player recognizes this, there's a lack of satisfaction, involved (at least, I think).
I scarcely remember anything about Portal 1, so I won't comment in relation to that game.