I know I'm late to the party, but I just finished playing Half-Life 2.
Wow. All I can say is that I've been missing out. It was thrilling from start to finish; I can't wait to get started on the episodes (I heard episode 2 is especially great).
Anyway, I found this video online, and I thought it captured the experience quite well. Be warned, there are some spoilers (wish I knew that, haha).