Hi mib. I have not done many tests yet, I’m not even sure I’m using OIDN correctly 
Anyway, at first glance, OIDN is doing an excellent job. The advantage of OIDN is that at low samples rates can achieve good results without visible patches and without losing much detail (Considering that a very noisy image does not even have much detail). But we know that Blender denoiser is mainly designed to eliminate residual noise from high sample rates renders. It will be necessary to test if for high sample rates and for production, which of the two is more stable for animation.
What I do not understand is if in OIDN things like Strength, Radius, etc. can not be configured, or is just that in Blender node it has not yet been implemented.
Here a simple comparison at low sample rate. You see blue sphere, OIDN is really having problems with those fireflies:
Original:
Blender denoiser (default)
OIDN
OIDN + Blender Despeckle node
By the way, @LordOdin has shared Theory Studio build for Ubuntu 16.04 / 18.04 distro based.
When you extract the file you will see in the folder the three files related to OIDN libraries in there (libOpenImageDenoise). You copy those three files to your /usr/lib. There is also Windows Build there. It also includes Scrambling Distance and Dithered Sobol Lukas patches.