I run with a minimalist shoe and wanted something with a very flexible upper and sole for trail running too.  Unfortunately, the tread around the heel is too thin to protect against rocks and roots without causing pain. The part of the heel that becomes the arch is finely treaded and extra flexible, so not so great for trail use.

The upper is nice and roomy even for wide feet though, and they feel quite comfortable. I normally wear a 7.5 and the 7.5 had a full thumb width at the end of the toe extra, so they run a bit bigger than most NB women's shoes.