Here's what I can tell you so far.
A) This is one of the greatest deals in gaming history. It's like Kirby Superstar, Except you're saving about $80 (if you were to buy each separately off of steam)
B)Half-Life 2 is still awesome, Gameplay, Story, and Graphics- wise (and I now have a computer that can support Reflections and what-not, making it even more awesome).
C) Portal is trippy, but I hear it's short (About two hours, but I'm having loads of fun experimenting with the portal gun.)
D) Team Fortress 2 was probably worth the wait. It's just like classic, but with a Pixar-like artstyle and comedic characters. This game doesn't feel like a tacked on Half-Life Mod anymore; it now has its own feel. This game is no longer a bland online-game; you can see the obnoxious expressions on your team-mates and enemies faces as they blow each-other to smithereens. My Favorite character: The Soldier, just because he has that helmet that's about a size too big for his head. This game is just pure, ignorant chaos, and I'm loving every minute of it.
I haven't played the Episodes yet, but from what I've played so far, the value of the Orange Box is worth those games alone, especially if you haven't bought HL2, yet.