I enjoyed it. I like how the fact that you don't know anything about the missing person is actually foreshadowing to the twist. The second day is the scariest imo, even though there's nothing much, but it is exactly because there's nothing you become on guard. The twist is good, and I'd even say that because the game made you very familiar with the library throughout the playthrough, it made the finale actually less stressful.
8/10 very well executed. Looking forward to more games!