The title is self-explanatory: I'm trying to get Deus Ex to work as vanilla as possible, using just Kentie's Deus Exe. Even if I install the new OpenGL renderer for Deus Ex, if I try to change the brightness level, the preview doesn't show any significant change other than reverting the resolution to 640x480 after confirming the change in settings.
Has anybody managed to get the OpenGL Renderer to work? I'm fineish with D3D10 as it is, but it's a bit too... Bloomy (I've fixed the stuttering issues in-game, but the menus are too bright and lowering the brightness to the point where the menus are ok, makes the game too dark)

I think you can disable the bloom effects by going to the advanced settings menu (press 'T', delete the "Say" command and type "preferences", press Enter).

Did you find a fix for the OpenGL renderer's brightness issue? I have the same issue and I also can't get the DirectX 10 or 11 ones to work, both default to the software renderer.

Try one of the many Deus Ex launchers. They let you pick the video backend.

I'm using OpenGL and had no problems except a couple of flickering textures in the intro cutscene (on the floor next to Simons and Page).

OpenGL makes the lightmap transitions between light and dark a bit smoother than the stock D3D, hence my preference for it. The only major downside - no Vsync or framerate cap by default, and you can't enable those through DeusEx.ini either. Forcing Vsync in the GPU control panel does the trick.

As for Kentie's launcher, I've tried it at one point but couldn't get it working.