The alternative of a "flat" spin suggesting a "pancake" impact has also been made, (the theory which has suggested that that is how the VS broke loose - upon impact, "tilting back" and fracturing the rudder structure - I submit that the tail-structure in that area is far more frangible and would do little to no damage to a vertical structure striking it from the top), but such an impact would result in very high 'g' loading so one would expect far more deformation of the larger parts seen in the photographs than is evident.
There is a common aspect to everything seen in the photographs; the structures are all relatively light in comparison to wings/engines/horizontal stabs/landing gear. Perhaps, like Challenger, (and as has been suggested here by various posters before), these lighter parts fell out of the main, heavier structures which had already failed into a number of open sections and continued to fall for many minutes with a comparatively, (and obviously) benign water-impact.
If the aircraft impacted the ocean in a flat spin, just to compare, this is what wreckage looked like in an accident involving a large (500.000lbs) aircraft when losing its vertical stabilizers in a collision. This resulted in a flat spin 16 seconds after losing its verticals. The first link shows the sequence of events in that accident, the second link is a series of images of the wreckage, confined to a relatively small area:
Crash Sequence of the XB-70
LIFE: Xb-70 Wreckage - Hosted by Google
Subject aircraft impacted the ground relatively flat. Its structure was mainly titanium semimonocoque and stainless steel honeycomb sandwich panels. Therefore, materials can not really be compared with the wreckage of AF447 but it does give an impression of the damage done to an aircraft destroyed in a flat spin.
Green-dot