Yeah, as soon as you care about more than one game, the Orange Box is the way to go. People will argue both ways, but an extra copy of HL2 was to me, free. I didn't own Ep1, and pre-purchased, so for $45, I got four absolutely awesome games. I gifted my extra copy of HL2 in the gifting thread (great thread idea IMO).
And Team Fortress 2 is so damn awesome. They really had quite a game to match (Team Fortress for Quake), but they did it, even if it took 10 years. I'm very glad of the art style they went with too. When I've looked at old TF2 screenshots, back when it was named some Brotherhood game, not only did it look like crap (HL1 engine it looked like), but it would just seem stupid to be playing TF2 with realistic graphics and gameplay.
TF2 alone, even without singleplayer, is better than most games, so it is worth it like a regular $50 game to me. The map selection is a bit limited (need some more damn CTF), but as was the case with CS:S, DoD:S, I suspect we will see some more maps in the coming month and years.
I really haven't played much else out of the Orange Box ever since I got in on the TF2 beta in the middle of September. TF2 is that good. But I'm enjoying Ep1, and Ep2 seems to be even better, and Portal is great for the 20 minutes I put into it.
Even if you don't like the episodic content, or think Ep2 is too short, or Portal is too short, even consider if TF2 is worth $30, Ep2 worth $10, Portal with $10, you are at TOB price, and you could consider HL2 + Ep1 for free (so may as well give it to a friend or gift it on here). And they are worth more than that IMO.