I will succumb just this one time to the Steam-honored "pros and cons" review style:

CONS:
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- In our jaded gaming society, where we just price vs. hours, at $10, it is very short. At a very leisurely pace, you'll be through your first playthrough in under 3 hours. And there's very little replayability.

- The story is a trifling thing, heavily telegraphed and perhaps not entirely satisfying.

- In my brief time, I've experienced at least three game-breaking bugs where I had to reload to make progress.

- It is most definitely a "walking simulator", complete with all of the limits and frustrations with which the genre comes loaded for bear.

PROS:
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+ In the brief playtime it offers, it's the most achingly beautiful walking simulator I've ever seen. Though I warned against the lack of replayability, I've already played it four times, just because of how astonishing and compelling the experience is. And for that reason:

+ It is the greatest cave exploration game of all time.

I mean, if you know what you're buying into, it's just... it's wonderful.

This game represents the death throes of the walking simulator, and what a tremendous, unforgettable way to go out.

Woefully underappreciated.