a few small crits:
Not everyone has played the original Portal, so some of your appeals to authority on that matter would be off-putting to someone new to the game (in general it's good to avoid to saying things like 'as we all know-').
I like your premise, that playing the original enhances and sabotages the Portal 2 experience, but if your piece is meant to compare and contrast, maybe it would be a better conclusion?
Otherwise, I think this is a fine first draft.
Welcome to the forum, btw!