The price.

[Dry]

£6.99 for a 40-minute game. And that's with taking time to completely explore the island in all of the phases.

Regardless of whether or not you consider this to be a game (I'd call it more of an art experiment) the amount of "gameplay" you get for the price is hilariously bad.
Yes I'm sure most of us got it on humblebundle (myself included) but the steam store price... maybe if it was 1.99, I could recommend getting it when it's on sale for 50% off; and it would barely be worth that. But charging half the price of something like portal2 or deus ex 3 for this... amazing.

[Psalm 38:5]

While I might disagree on the values you mentioned (I think it has more than 40 minutes in it), I'd have to agree that it seems quite expensive.