The info that we know about Snoke is that he is someone/something very old, that 'old' could be 300 years old or could be 3000 years old yes that much we know for a fact that Kylo is sporting some "ancient" lightsaber design who revealed to him that ancient design I wonder.
We also know Snoke is sporting some never seen before powers in his moves, like that freeze ability he probably showed Kylo and some info out there from boxes with toys or something like that if you search for them will give a little line of info.
He is floating Rey probably at the end of the movie judging from her clothes she isn't wearing the ones from the start (also the ones from the Kylo hand out, that is editing in my opinion).. so he has more advance stuff then just force freeze he can float you while torturing you in old EU stuff if you get tortured and bombarded with dark energy for a long period of time from a dark force user at a master level you could also turn to the dark side just to be able to survive it like a self defense mechanisms but a perfect gateway for the bad people to change your software in a way. We have more theories with that scene, hope we don't get it as a cliffhanger for 2 freaking years.
Luke ain't just scared / traumatized because of his students and nephew he could very well be in cave talking with Yoda, Anakin, Kenobi, Qui Gon on what the heck to do about the ancient damn force user from the unknown region that is older then all of them combined and managed to manipulate his own blood against him, how the heck does he even fight back.. I guess this girl appeared.. that just means an easy +1 for Snoke or what, for all we know Snoke maybe was close in even turning Luke maybe that's why he is so screwed up.
I think I should put a spoiler tag on off this just to be safe.