I've used it to look at past homes, re-visit sights on my road trips, do research for my job ("Yep, Malibu has a Ralph's -- probably a pricey one"), see what's changed, see what hasn't, and discover the often-unexpected places where the Street View camera was carried by a person down paths, across parks and and through train stations. (Choose "Paddington Station, London" in Google Maps. You can take a walking tour of three floors of the station.) I once used it to reassure myself that a Rancho Bernardo, California neighborhood where I lived until 1981 didn't burn down in the 2007 fires.
Street View somehow flattens out hills, probably due to the fish eye lens effect. You only ever see dry weather, because the Google Street View car drivers take down the camera when it's about to rain, or apparently funky things happen to the image or (worse) the camera. I make sure to note the date the car drove through an area; I think the oldest images I've seen while looking this year was from 2007. There are occasional photo bombs: I saw two men pose in muscle-flexing moves in front of a house as the car drove by. I've yet to see an organized, planned group shot caught by Street View; I hope to find one one of these days. Glitches happen: on a Boston waterfront road, you'll go with one click from the surface into the tunnel to Logan Airport. REALITY BENDS.
Now I wonder if Google Street View has ever captured accidents. That's a morbid thought: I can also wonder how often Google Street View has captured a nice hug.