Portal, as a franchise, has made a lasting impact on geek culture in general, I think. Already we see the old cake and "Still Alive" memes replaced with images of potatoes, lemons, and SPACE; new "in-jokes" floating all over the internet, officially zeitgeist-ified by anons everywhere.
Portal 2 was an amazing game. It captured me like it captured so many others out there, and for a myriad of different reasons. There's a lot of "good" to be had in Portal 2, in other words.
For me, the real charm of Portal 2 was the personification of Aperture Science itself. The puzzles were great, challenging and clever but not overtly difficult, and the writing was superb, with hilarious writing and voice acting for all three "major" NPCs, but where Portal 2 really excels is the subdued method of story telling. Valve doesn't coddle the audience with overt reveals. The (literally) buried secrets of Aperture are simply presented to the player, put on display, a tomb frozen in time for the audience to explore.
We, as players, put the pieces together. It soon becomes apparent to the player that Aperture isn't just a science lab, it's an extension of Cave Johnson himself. The eccentric shower curtain salesman turned super scientist, Cave literally built Aperture Science from the ground up. It shows an insatiable desire to prove something, to someone, anyone. Consistently in second place (to Black Mesa), he keeps pushing the logical limits of responsible science; his obsession became his undoing.
When we, the player, hear about the ridiculous experiments that ultimately leads to Aperture's bankruptcy and subsequent testing on the homeless and its own employees, we laugh. It's clever black humor, and the experiments behind those vitrified doors in the basement of Aperture are presented in such a way that we can't help but laugh. However, much more startling, we believe that these experiments are grounded in the logic of the game's universe. We believe that they were actually conducted, no matter how ridiculously absurd their premise. Aperture Science is Cave Johnson's reality, a bizarre world that Valve skillfully brings to life for us to unravel and explore. The depths of Aperture are both fascinating and frightening, a true vision of super science gone wrong.
Then again, the worst thing that came from Aperture Science was the wholesale slaughter of its employees via neurotoxin. Black Mesa inadvertently enslaved humanity to the Combine. So maybe Cave got the last laugh after all.