I find the bing imagery much improved over the previous base. Aside from scale, the big difference in the imagery is seasonal. Snow cover and long dark shadows in the older photos made many areas appear to be black or white, and properly locating roads, let alone trails, was nearly impossible without some GPS assistance.
I'm currently updating the Gunnison and San Isabel National Forests using Potlatch 2 and memories from trips through the area. Also double-checking tags with the aid of government maps. Even US government maps do not always agree with each other, so I will not modify the tiger_review tags without further ground verification.