Outlast is a pretty good game. The last chapter is kind of a letdown because the Walrider isn't particularly frightening, but other than that the atmosphere is usually well crafted, and the infrared camera mechanic really adds to the experience. If there's one thing you'll see more than anything else though, it's Saving ... in the corner of the screen.
I'm not one of those people who despise checkpoints in general. In fact, I find frequent checkpoints an important feature because I for one don't want to replay the entire level ten times before nailing it. Playing the same thing over and over gets real frustrating real fast, especially in games where you might suddenly be blown to bits by a grenade you had no chance of noticing. But this comes with a great big caveat: it severely diminishes any tension the game is trying to build up.
As with all horror games, the moment you figure out its patterns and limitations is the moment you stop fearing it. I remember how I was scared shitless the first time I played the original Slender, but with a few tricks — in particular, slow and calculated movements — it naturally lost much of its tension. This applies to Outlast as well; once you figure out that you can just hide in the same room again and again without the enemies getting any smarter, any actual fright is effectively destroyed.
Add to that the frequent checkpoints where dying robs you of very little progress and you realize that the best strategy might actually be to carelessly explore the level, reload and know exactly where to go and where to hide. That can't be good for a genre that pretty much lives and dies by its ability to keep you on the edge of your seat. At least with Slender, you had to start over if you were caught, so that actually carried with it some consequence.
Don't get me wrong, Outlast is still a good game, and I think one simple tweak could help the horror along: just don't show the checkpoint notification. Without it, you wouldn't know how far back dying would take you. While you'd probably still figure it out eventually, it would be less obvious from the get-go. A more involved tweak would be reducing the checkpoint frequency by half, but then you're walking a fine line between tension and frustration, especially once the difficulty ramps up towards the end.