From this episode we learned:

Gale Bertram is NOT Red John.
Brett Partridge is NOT Red John
Reede Smith is NOT Red John

And we also knew:

Bob Kirkland is NOT Red John.

That leaves us the Sheriff, Ray haffner and Bret Stiles.

Is not the Sheriff. 

Is between Ray and Bret. But I think that none of them is Red John and we are going to be surprised!