Besides reflection support in the shader compiler for Direct3D, there is now support for changing network passwords, tests no longer attempt to cope with odd behaviors in Windows 9x, and there's a number of MSHTML and MSXML improvements. There's also the usual assortment of bug fixes.
This reflection support does include implementing some functions within the Direct3D 11.0 shader reflection class, but the overall Direct3D 11.0 support is still a ways off. Of course, they could also still hook into the Direct3D 10/11 Gallium3D state tracker as an optional back-end for native execution on the GPU rather than translating the calls to OpenGL. This latest Direct3D shader compiler work was done by Rico Schüller.
The list of bugs fixed and other information on Wine 1.3.15 is available at WineHQ.org.