Darkly hilarious writing, innovative gameplay, and intriguing additions to the Half-Life universe make it a winner.
First, this game is *not* too short, it's just right. Any longer, and the story would be stretched thin. The fact that it leaves the player wanting more is just a symptom of how awesome it is.
Second, I wand to see more of GLaDOS and Chell. These two characters, especially GLaDOS, are really interesting new additions to the Half-Life fictional universe. I'm itching to know more about who Chell is and where she came from, and to understand the agenda and motives that make GLaDOS do what she does. More!