This may well depend on your internet connection speed and where it is you are looking at. Most of the States is in Hi-Res but only major cities in UK plus a couple of other areas.
To really check if it's working go to London and slowly zoom in, letting the streaming bar at the bottom of your window get to 100% to get the clearest picture.
To let you know what it should look like, at 500ft above Buck Palace you can make out a coach and other vehicles in the grounds and the tourists massing around the gates.
As for not being perfect yet, some of the places won't get much better than they are.
Try the Twin Tower Site in New York. I was highly impressed at the quality. Trucks, Cars and Excavators clear as a bell, but if you look closely you can also make out the people, as you can if you visit the EPCOT Centre in Florida, which is only half in Hi-Res.