Frustrating and unfun.
I filled up the gem meter just as the boulder was about to crush me. Indie punched it... and he died. So that's nice. Apparently, even though I collected enough gems on the brink of death, the game isn't going to let me continue. How incredibly frustrating.
Another frustrating feature: The fact that missing even a single gem, no matter how close to full your gauge is, means you lose it all. Meaning if you regularly collect 8 or 9 gems in a row, and can't quite manage to get the next because it spawned just a little out of reach, you're basically fucked. In fact, you get punished less for collecting a smaller chain of gems before a full-10-chain. There is a valley between playing badly and playing well that receives the most punishment.
I know this is just a quick, cheap, tie-in game to promote the upcoming documentary, but tell me this: Why would I want to watch what this game is promoting if I dislike it so much? So, consider addressing these problems in an update.