DPReview has posted its in-depth Nikon D7100 Review.
Notably, DPR shows that the D7100 has greater shadow and highlight dynamic range compared to the D7000. In the ADL Extra High mode, the D7100's shadow range is off the charts, and its highlight range is almost at the edge of the chart.
Also of note is the shape of the D7100's tone curve. With ADL off, the D7100's tone curve has a softer shoulder (more gentle highlight roll-off) compared to the D7000 or D600.
The review doesn't mention banding in extreme exposure adjustments (but neither does DPReview mention banding in other cameras that have it, such as some Canon DSLRs).
Nikon D7100 Hands-On Real World User Review
Nikon D7100 Low Light Teaser
Nikon D7100 FAQ and Helpful Links
Nikon D7100 Shadow Recovery
Nikon D7100 Real World Dynamic Range
Nikon D5200 and D7100 Band-Aid: Solutions for Banding