I actually like EP2 more than EP1. I actually played EP2 first, and after I went back to EP1, I was kind of disappointed. EP2 storyline is great, and the graphics are AMAZING! The lighting effects alone make the game like 30x more creepy in the dark. Movable physics (as well as static) objects cast shadows under the flashlight and they actually look good :O. There is also a solid story line, so you never wonder wtf just happened. (Even if you skip EP1 and go straight to EP2 like me)
Portal is pretty hilarious, but not all that long. Took me maybe 2-3 hours to finish it from start to finish. There are bonus maps though, which are crazy hard.
TF2. I didn't like it AT FIRST. It felt way to fast paced for my taste, but I eventually learned what classes I liked and now I dominate in the game. Sniper and Spy, baby!
If that isn't enough, they throw in EP1 and the full version of HL:2 and even allow you to give your original copy of HL:2 to a friend (if you owned hl:2 previous to Orange Box)