For those who have portal 2.( I'm not going to advertise here) give me your feedback and what you thought to be the most challenging level. If this is advertising then the mods will have locked the thread. As far as I'm concerned this is just asking what people felt about the game.
11) Please don't advertise for other games, forums, programs or services outside of The Powder Toy here. We have enough activity dealing with just Powder Toy.