*In which I update my review of Portal because the last one didn't seem very clear.*
Portal is a game in which everything about it is perfect. I don't wish to throw that word around lightly, but everything from the beginning of the game to the end is perfectly executed. It's simple. Simplicity does not always equate to boring, however. And I feel that Portal 2, in it's need to be grander than Portal, suffered from issues that did not occur in the original.
The writing here is superb. And unlike the successor, It strikes a neat balance between humorous and character developing. The overarching narrative is simple. A.I. kills everything in charge, and the only thing she can do in her spare time is test. You happen to be her new lab rat. Because the narrative is simple, GlaDOS' character is the focus. Her mental state is conveyed through voice overs. She taunts you in the beginning in which she knows shes in control. Her tone of voice changes later on, as you begin to escape. There's a lot of pleading most of which involve cake. The fantastic thing about this is her dialogue never interrupts gameplay. All that is needed to know about GlaDOS is told clearly by her tone and dialogue hints. The narrative, while simple, has it's fair share of surprises. You eventually discover one of Doug Ratman's dens. A previous scientist now turned lab rat. You are shown the affects of isolation and this small moment changes your goal throughout the game. You now wish to escape, and, you are much more wary of GlaDOS. You question the legitimacy in what she's saying.
The design of the gameplay is nothing short of spectacular. It's tutorial is ran throughout the game as it constantly teaches you something new. Because it always teaches you something new, it keeps the game from getting boring and repetitive. The environment it clean and similar to Ico, can be considered bland. This however, serves the gameplay. The simple environments keeps you focused on solving the puzzle, and makes them more difficult. Because Portal 2's environment had a lot going on, the puzzles were a bit more obvious; as you could just look for a white slab and solve it that way. Each puzzle is creative and takes full advantage of the capabilities a gun that shoots portals would have.By the end of the game you have been exposed to each mechanic enough so the boss is challenging, but obvious as to what needs to be done. This was the first game I played which made me realize how amazing games can be, and how unique their storytelling methods are. Great game, something im comfortable giving a 10.

tl;dr I really like Portal.