Okay, I just played Portal, which has seen a bit of discussion in the IF world, so it might be interested to comment on it here. Also, this game has been hailed as something that can evoke great emotional responses through effective storytelling and characterisation.
This is going to be completely spoilery, so if you don't want to be spoiled, don't read on.
The game is certainly too short and too easy; there wasn't a single puzzle in it that had me stumped for longer than a few minutes. The final boss fight was exciting, but not terribly hard either. (F6 and F9 are your friends.) I hope that the advanced maps are more challenging; otherwise, those portals are a brilliant puzzle idea left woefully underexplored.
The player character is constantly pestered by a female voice that talks her through the tests, but reveals itself as unreliable in the first thirty seconds. The writing here lacks all subtlety. The voice tells you things like: "Your safety is ensured if you ***static***", which really is a cheap trick. Valve also decided to use 2001-style modulations of the voice's pitch, which suddenly drops from high to very low on several occasions. But in 2001 this happened once, in an emotionally gripping scene; in Portal, it happens all the time, and is just one of a hundred signs thrown at us that scream "Look out! The computer is insane! Don't trust it!"
The entire game consists of such shouts. You find a secret room were someone has written warnings on the wall in blood. All right, I can't trust the voice--I understood that already. Then, in case we missed it, we get treated to another twenty places where people have written warnings on the wall in blood. Identical warnings. This gets very tiresome, and destroys any emotional involvement with the story that might have been achieved if the designers had opted for a subtle disclosure of what was going on, rather than beating me over the head with the stick of obviousness.
Emotional involvement, then, there is none. One especially lauded scene in the game is where you have to sacrifice a metal cube with hearts painted on the side. This is supposed to be an emotional moment, which makes you feel guilty. It does not. The things I have to sacrifice is a metal cube with hearts painted on the side. I don't care about a metal cube with hearts painted on the side. (The emotionally manipulative voice and the emotionally manipulative designers at Valve don't succeed in actually manipulating my emotions, mostly, I guess, because their attempts are again so incredibly obvious.)
The final scene is okay. It doesn't have the impact of Hal's death in 2001: a Space Odyssey, it doesn't even come close, but it's not bad. It might actually have been good if I had cared about the AI, or about the player character, or if I had understood what the hell was going on, or if I had seen the AI in a sane state before I saw her mad. As it is, the song over the credits is more gripping than the game itself.
So, it is a nice puzzler, recommended if you want to spend a couple of hours solving puzzles. (Though Professor Fizzwizzle is more fun in that respect, and also more challenging.) But a game that can evoke great emotional responses through effective storytelling and characterisation? Not at all.