One thing about the half-life series is it takes itself seriously. In that alot of what happens even if it is a "game-ism" (being able to withstand being shot multiple times) it's still worked into the game as being "real". Melodramatic acting isn't too common here. Your not going to see extreme "GASP!" type emotions being shown, alot of it's incredibly subtle.
With that, note that throughout the game you Gordon Freeman already have a reputation for what you did in the first game, and people look up to you. Notice how everyone suddenly straightens up once they notice who you are. They hold back their personal emotions and instead show admiration and respect towards your character.
But watch how things change with you and Alyx as the game goes on. Again it's subtle. It starts kicking in at Nova Prospect.
I've been playing through various parts tweaking the game for another run through since last year when it was originaly released and I've installed Fakefactory's excellent high-rez skin packs. I was playing last night and I looked up and the scene I was watching looked nearly phot-realistic. It was Alyx hacking a console inside a combine chamber. Through a combination of how well the lighting was working in that room and on her, and the excellent animations and character model with the high resolution texture for a second I realized what I was looking at at that moment looked almost completely convincing.
There are some seriously jaded gamers here. I think part of it is the market's fault. Once someone comes up with a hit a bunch of "Me-Too!" games jump on the waggon. By the time Half-Life 2 came out we'de seen our fill of attempts at being the next Half-Life already. Makes it harder to appreciate a game that doesn't try to go over the top in what it does, but instead shoots for a really really refined presentation. I think Half-Life 2 is well deserving of GOTY, Far-Cry made a great stab at best FPS as well. I enjoyed Doom III, though it was very old-school in too many ways, but considering it was a retelling of the original Doom the old school aspects end up working for it anwyays...