I had blue fog in Silent Hill 3, but I was playing a new game. However, it was an extra new game. I still saw a lot of framerate stuttering and second-long freezes. One time, my game actually did freeze when I got hit by an enemy. Other than that, the voice-synching is much better, but this is still a terrible port.
As for Silent Hill 2:
-There was a bit more fog than before, especially during the Rosewater Park scene. I did see the water "vortex" during the boat ride, though. However, it was more noticeable in cutscene rather than gameplay.
-The voice-synching was improved, and it seems that they altered James' breathing for the new voice-over so that it doesn't sound like sawing a log.
-The first Pyramid Head cutscene was fixed and plays properly.
-I also noticed the horrible shadow effects in this game too. I don't know why they're so jagged.
-Part of the texture for the "Abstract Daddy" boss and "Doormen" enemies disappeared when they died. Their bodies were visible, but the fleshy part of the frame vanished as soon as they hit the ground.
-That weird teeth-thing was still visible in Maria's eye at the end.
-The running animation slow-down was fixed, but I saw a lot more framerate stuttering and slowdown than SH3.
-The sound of blaring horns in the Historical Society has been restored.
Overall, Silent Hill 2 was the lesser of two evils in this collection and that still seems to be the case post-patch.