From what we can see [imaged], it would appear as if provided are some in-depth statistics, along with an expected layout change (which includes a rounded layer, it seems). Other than that, we can’t seem to find anything too special.
Understandably, Bowman has been conservative in his image postings of the Twitter redesign for obvious reasons. As a matter of fact, it’s the only image we’ve seen thus far, though we would fully expect more teaser images in the very near future.
Until then, keep patient.