I've played through about six hours of The Evil Within so far, and it appears to find itself comfortably situated halfway between Outlast (my bar for survival horror games) and Resident Evil. It isn't as consistently tense or scary as Outlast, and while it shares a lot with Resident Evil (obviously), it does a better job of severely limiting your ammo and resources, which makes it a much more frightening experience than the more recent RE games.
I also felt the game regularly switches pace, almost so much that I wondered if the The Evil Within couldn't quite decide what it wanted to be. In one area, you'll be stalked by a homicidal freak with a chainsaw, from which you can only desperately run, and in the next your sneaking through the bushes performing Sam Fisher-esque stealth kills on "zombies" with poor relatively poor AI. And from there, you jump into some serious paranormal shit, and then back to something else completely.
The Evil Within is all over the map, both in location and general atmosphere. It does manage to be both entertaining and scary, despite that, and despite the fact that it pulls in practically every modern survival horror game trope in the process.
If you wanted another Amnesia or Outlast, this isn't it. It's broken up too often by outright combat and traditionally bewildering "Am I hallucinating this?" story elements. If you wanted a new Resident Evil... well, I think we're closer to the very first game here, or maybe shades of RE4. It feels darker and more claustrophobic than I remember most of RE4, though.
By biggest overall criticism is that the third-person RE camera just doesn't work for the portions of the game that are trying to be Outlast/Amnesia. Your inability to easily peek around corners without revealing yourself was a constant source of frustration for me as I tried to avoid walking face first into a big scare. The camera also refused to cooperate in tight spaces on regular occasion, sticking my view inside walls or other objects. It never became so troublesome that I wanted to stop playing, but it was there.
You can watch the entirety of my 6 hours of livestreaming the game here, or I've also put together a supercut of some of the best scares below.