The Orange Box is great value for money!
+ Plenty of choice
+ You'll definetely find something you like
+ Good value
Negatives
- Long installation and update times for some
The Orange box contains Half-Life 2: Episode 1 and 2, Team Fortess 2 and Portal, all of which are good games.
Half-Life 2 is a great futuristic shooter, Team Fortress is a massive online class based FPS and Portal is a very clever puzzle based FPS.
As I said, your bound to like at least one of the games in the box, for seperate game reviews I reccomend checking out the games individually as if I were to review them all now I'd be here a long time.
The one disadvantage you may find is the waiting, all games put together totals to 20GB, which is huge!
Fortunately they give you the option to install which ever ones you want (for example, just Team Fortress 2, or just Half-Life) to play the games it'll make you install Steam- from here you can then install/uninstall any of the games in the Orange box at any time, however you'll need an internet connection.
Update times are also a pain, Team Fortess 2 took me nearly 3 hours to update (at 130kb/s) which isn't great when your excited to just start playing your new games.
However I'd highly reccomend buying the Orange box, you won't get a better deal with any other package.