Here are some of my comparison shots...
1st image is default, 2nd my version.
I think it looks a lot better, obviously it is subjective and the look will depend on your monitor and its settings.
There are my injFX_Settings.h tonemap settings.
Code:
/*---------------------------------------------------
TONEMAP
--------------------------------------------------------------*/
#define Gamma 1.20
#define Exposure 0.00
#define Saturation -0.40 // use negative values for less saturation.
#define BlueShift 0.05 // Higher = more blue in image.
#define Bleach 0.10 // Bleach bypass, higher = stronger effect
#define Defog 0.055 // Strength of Lens Colors.
#define FogColor float4(0.00, 0.90, 0.00, 0.90) //Lens-style color filters for Blue, Red, Yellow, White.
I like the darker, less saturated look.