Labels exhibit several very interesting characteristics in Autodesk Civil 3D 2005.
1.) All text related to objects can update in size when the drawing scale changes.
2.) They can be set to world orientation or view orientation.
3.) Bias controls at which angle they flip. Unlike LDt they can flip at a user specified angle, i.e. 110 degrees, instead of only at just past 90 degrees.
When viewed through a viewport...
1.) Labels can appear horizontal in different views, even though those views have different orientations.
2.) Labels can appear the same height in different views, even though those views have a different zoom scale factor.
The ramifications of these two last capabilities is a user only creates one set of labels. But, those labels will appear correctly in drawings with different scales and orientations.