I use that daily at work. The images are from high res aerial photographs for a lot of the populated areas, and it reverts to satellite imagery in the remote areas. I use it a lot because you can overlay the cadastral data (property boundaries, lot numbers, easements, etc.).
Isn't that why they started charging to use Nearmaps?
I heard it was because lots of companies (mostly roofers) using it to quote jobs. Nearmaps got wind of people making money from their free product and promptly put up a paywall.
Or so I was lead to believe.
Pity, at the time they had the best high res images. Google only had satellite images back then, I guess it's probably much better now though.