So - How powerful is Snoke, exactly?
(Obvious spoilers)
So Snoke's story clearly hasn't turned out the way we thought it would (unless if Abrams does a switcheroo and brings him back).
So, what does this mean for his placement in the canon?
From what I can tell, we know:
1. He's weaker than Luke, at least as of the last the galaxy had seen him. The Visual Dictionary states that Snoke thinks only a Skywalker can kill Luke, e.g. he personally isn't up to the task.
2. He's vastly more powerful (in actualized ability) than Rey and probably by extension Kylo, though we don't have a clear picture of how strong these two are either except that they're almost certainly weaker than Vader. We can extrapolate from Kylo's potential + years of training that he's probably pretty powerful, but by how much, it's difficult to say.
3. His Force bridge and telepathy seem to be pretty impressive. They're almost certainly above the likes of, say, TPM Maul or AotC Obi Wan. Not sure how far above it puts him though.
4. Andy Serkis claims Snoke is more powerful than Sidious or Vader because "his resources are limitless" but that doesn't make much syntactical sense and I'm not sure how much stock we should put in actor opinions (unless if Mace Windu is still alive).
5. It's not enough to say "he's featless so he's weak", you know, absence of evidence != evidence of absence. Without the evidence to back it up it's unlikely he's Palpatine level, but it's not a given that he's some random weakling either.
6. I get the impression from the way Luke, Han and co. talk about him that he's not on the level of someone like Palpatine. Luke saw Palpatine as a threat on a galactic scale, but he just sort of is like "oh Snoke is manipulating Kylo" and I wonder if he bothers that much to hunt him down pre-TFA.