It made it so shadows will appear from second story walls and stuff like that. Big deal.
But by default, shadows would always fade out after a set distance. Trees in the distance, however, have "dummy shadows" under them which are always there- that way your town doesn't look ridiculous from long distances.
However, the distance that shadows fade has gotten a LOT smaller. It used to be tolerable assuming you didn't move the camera too low, but now it's just ridiculous. When staring at a sim, the shadows just 6 or 7 feet away start to disappear. I was trying to find a fix for this a long time ago (to make the shadows fade at a MUCH larger distance) but came up empty handed. The shorter distance means that the dummy shadows are visible a lot earlier (see the space between the lots), and they just look horrible from this distance- Because they AREN'T SUPPOSED TO SHOW UP SO EARLY!
Indoor lighting seems different, though I'm not sure if it actually is or not. I do know that now, lighting isn't rendered constantly. That is to say it's a lot more basic when you first switch to a floor, then it goes back to being how it should. This too is pretty annoying, but way less so than the outdoor shadows.
Here you can see the progession upon switching to the first floor from the second, as the lighting gets noticably more detailed:
You can see it easily on the fireplace at the top, or the lighting from the door on the right. It goes from minimal shadows/lighting, to half/half (screwed up in a lot of places), to proper, and it's noticable- every single time.
I wonder if they'll ever manage to get it right.