If I'm driving somewhere new, I'll use it to identify landmarks for turns. While I'll often have the spoken map directions going on my phone, if the intersection is complex, streetview can help me get into the correct turn lane.
I wanted to use it for Germany prior to a trip a couple of years ago, but it looks like very little of the country has coverage, which is annoying. But it's their country and if they don't want camera cars photographing everything I can understand that.[0]
[0] I had a neighbor get divorced because of streetview. Back when it was new, the first thing everyone did was look up their home. Well, my neighbor saw a custom motorcycle parked out front that was not his.