I must say, the HL2 graphics really impressed me. Not sure if there is any difference between the CD and the Steam version (I got the Steam), but I never noticed any of this gliches. The voice thing you said wasn't really an issue to me either.
Anyway, HL2 is yet another game worth playing. :-D

Gotta say, I really didn't find loading times that big of a problem. For me, they were 20-30 seconds. Maybe 40 seconds tops on the bigger levels. I, oddly enough, didn't get any of your errors the first time through. I did feel that the AI was hyped to be better than it was. But I still think this blows away any other PC gaming experience I have ever had (except possibly Riven, but thats for different reasons, and I doubt most other people think that).