I was hesitant with Chapter 1 as I wasn't quite sure what to expect... which turned out to be a lot of fumbling in the pitch dark in a few "Penumbra-esque" environments. Once I got the hang of what was going on I found myself entertained, but not necessarily thrilled. I was concerned that the next chapter, not to mention the following 3 and 4 were going to be just the same, but maybe with some skins swapping and cookie-cutter levels/puzzles.
Then I got to chapter 2 and was blown away. This isn't "in your face" horror, this is subtle. The game isn't in it to make you jump out of your seat, but to let you plod along then suddenly make you sit rigid and let out a panicked "#$@!". Chapter 2 was magnificent at its pacing, letting me get just confident enough to be speeding around right before slapping me in the face with a big horrible surprise.
After completing the first two chapters I'm super happy with the game. These chapters are not just copy/paste jobs, but offer full changes in environment, puzzles, interactions, and 'enemies'. From what I can see the last two chapters will also differ greatly from the first two, making each chapter a unique play experience, and horribly eerie in its own way.
However, as for the bad (or atleast the not-so-good) the game offers the ability to change keyboard controls, but not for all functions; so when I bind the horrid WASD to the more preferred ESDF I couldn't understand why my torch kept going out so fast - Oh... F is bound to pull-out/put-away torch, but there's no option of that in controls, and is a forced keybind... gotcha.
On top of that, the story is a little too vague. I do appreciate the fact that the story is just subtle and vague enough to not be an "insult to the gamer's intellegence" by being spelled out and shoved down your throat (and actually works very well to let you figure it out in your own interpretation), but it's so vague that I found the continuity confusing, and most specifically for Chapter 1, that there was no successful completion to my mission (that made any sense to me at least).
The last negative is the price point. While the game was a worthy purchase for me, I bought it on a sale for pretty cheap. Had I of spent $10 on this I might've felt a little ripped off - why? I don't know... $10 isn't much and I certaintly got a few hours of fun out of this, but the game feels 'simple' compared to the other games available in the same vein (that are also available for quite cheap).
Still, despite some minor flaws, the game is short enough to not get repetative and interesting enough to hold your attention. While it may not be for everyone, fans of the horror-puzzle games (and most specifically, the third Penumbra game) will have a grand time with it... but maybe just wait for a sale.