The devil is in the implementation details. Are favorites/shortcuts in the same part of the screen? Are they in the same order? Does the dialog remember sort and view configuration between folders? Does the dialog differentiate between mounts, symlinks, and tangible files? Does it display networked machines properly? Are file icons consistent in design if not color scheme? The problem most people have (in my experience) is behavioral. The mismatching visuals is just the most jarring aspect that's easiest to point to.