I love Portal. I think that if you ask any gamer they will say that Portal is a refreshing step back from the typical FPS. Last night though, I wanted to through my PC out the window due to the frustration of the Challenges in Portal.
Let me draw a picture of what happened last night for me. First I was thinking about getting all the radio signal achievement and found that to be fun until I came to the level where the radio is in a little room with 2 timed doors. Now when I first played through Portal in 2007 I never tried to get myself trapped in that room because their were no walls for you to put a portal on and so I didn't know that Glados was going to open a trap door to let me out. Instead I spent one and a half hours trying to time it so I can grab the radio and jump out... This of course did not work :( Every time I attempted to do this I was crushed in a door. Needless to say when I was at my wits end I locked myself in the room and discovered that Glados was already prepared for that stupidity. After that I just threw in the towel.
The game is frustrating but also enjoyable enough that the frustration wont stop me from playing through to the end.