Vanilla Ori and the Blind Forest has great visuals - the design work is fantastic as is, but I was too curious and tried installing SweetFX with my preset I use in other games. The result instantly made me start a new game and absorb all improved visuals, never spend that much time admiring the job Moon Studios have done with the visuals.

Note that different monitors display colours in different ways, meaning that my SweetFX settings can be overkill in some situations. It also depends on personal preferences. On my TN panel, the game looks much better, although few especially vivid places became "too vivid". Can't say how it will look like on IPS panels which are known for better colour quality.

Here are two full-size screenshots with FX on and off to compare:
http://imgur.com/a/AENuV

Installation order:
1. Unpack the contents of the archive to your Steam\SteamApps\common\Ori folder,
2. Backup ori.exe just in case
3. Run ReShade Setup.exe
4. In setup program, select ori.exe
5. Close the application (even if it says that installation has failed due to some file not copied)
6. Start the game from Steam

Known problems:
Steam overlay may not work. Try restarting Steam.

Effects enabled:
SMAA - makes object edges look smother, not as useless in a platformer game as you may expect
Lumenasharpen - depends on SMAA, adds extra contrast on object/particle edges. This effect makes it a lot easier to distinguish moving parts of the picture from not moving - you'll notice a lot more movement on screen thanks to lumenasharpen.
Tonemap - brightness balance
Vibrance - extra vivid colors
Dither - some neat feature that makes color approximation more effective