So basically in this thread, everyone saying their graphics got better is everyone who have always run with HDR Bloom on. I don't, and I see absolutely no difference between OGL and DX9.
EDIT: Here are some screenshots, both using the exact same settings, apart from that the first is OpenGL, and the second is Direct X.
They are linked due to being 1440x900
http://gunrun.banpunchstudios.com/files/OpenGLRO.jpg This is the OpenGL screenshot
http://gunrun.banpunchstudios.com/files/DX9RO.jpg This is the DX9 Screenshot.
Both use the same ini settings. The only difference is that in DX9 you get proper lighting on the gun. In other words if you are stood in a dark place your gun is dark etc. Apart from that nothing is affected.
For a setting that WILL actually make your graphics a lot sharper, go into your ini file, and find the [D3D9Drv.D3D9RenderDevice] or whatever render device you are using, but if you have any sense it will be that one. Anyway, find that, and then look for the line UseTrilinear= and set that to True, then find the tag LevelOfAnisotropy=1 and change it to 4, 8, or 16. Neither of these should have spaces between the = and the value. This will result in less texture detail drop off, and when there is drop off it will be smoother.
This is the same shot as before, but with those settings set to their default values
http://gunrun.banpunchstudios.com/files/NofilteringRO.jpg
This is them with my values in place (I use 8, but 16 will result with even better textures, but more FPS loss)
http://gunrun.banpunchstudios.com/files/DX9RO.jpg
Please note the sharpness of the end buildings textures, and the pavement in front, and basically every texture that is past (and including) the tank.
EDIT: Straight from TWI's mouth -
(+Gunrun) Yoshiro Does openGL look any better or worse than DX9?
(+Gunrun) there is a topic in support claiming so, but I see no difference
(@Yoshiro) ...but if you mean in terms of RO
(@Yoshiro) it looks worse cause we don't have any shaders or functions
(@Yoshiro) the open GL is RO is the same as Direct X 8.1