The best part of portal 2 isnt even the gameplay mechanics, its the characters. Often I stop walking just to hear what GLaDOS and Wheatley have to say =p. At chapter six now and I kinda regret spoiling myself by reading the plot long ago because its actually really good.
Playing portal 1 first is a necessity though, there are quite a number of references to portal 1 that can only be fully understood (and hence hilarious) when it has had been played before,
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