I just bought it off Steam, and it's awesome. The ending song (which my friend gave to me loooong before I even knew the game existed) is pure win, and GladOs is probably one of the best in game characters ever, in my opinion.
Portal is related to Half-life because the chambers were created by aperture science, the rival company toward's Black Mesa, Aperture Science's ship, The Borealis, is found during the gameplay of Half-Life Episode 2.
The game was hard
but it was worth of finishing it
the chamber that needed to go to continues portals are the hard ones woah but again it was worth finishing it
i played it on my cousin's laptop
since my laptop is to weak for that kind of graphics
I like finding the parts where you get to go into the red areas behind platforms and seeing picture of the Companion Cube and the words written on the wall.