THE GOOD: Always the innovator Valve has employed a realistic physics engine to help devise new gameplay possibilities. Whether it's the ragdoll effect of a Combine soldier being blown up 20 feet in the air or using a gravity gun to carefully put together a staircase of wooden crates, the physics are the most impressive feature of this very impressive game. The AI of the enemies is no slouch either. Depending on the unit type, they will work together to flush you out with grenades, catch you in a crossfire, and/or find an alternate path to outflank you, including having one of those fast zombies crash through a ceiling window which scared the crap out of me! Graphically I knew that HL2 was going to be good but it still amazed me to see the nearly photorealistic textures and intricately detailed levels and characters.
THE BAD: HL2 is a very linear game which helps the story maintain it's pace but hurts the immersive qualities somewhat. I didn't find the setting or story to be nearly as intriguing as that in the original HL. Also, while the vagueness of the orginal game could be excused many things in HL2 are simply left unexplained. After hearing how HL2's story was penned by a professional writer it's dissappointing to have so much of this supposedly great story be left to pure conjecture. The end game was anticlimatic and almost as big a dissappointment as Halo 2's non-ending.
BOTTOM LINE: HL2 couldn't possibly live up to the hype built up around it but I was still more than happy with the finished game. It's everything you expect a next-generation game to be and because it's Valve I know that the next iteration of the HL series will be worth the wait.