OK its a John Carpenter ish homage, different enough in places, but some jumps and past camera shots are pure JC stuff.
Budget wise its low, but filmed and shot well, effects are also well done, and 90% are practical.
The first half is the better, yes the action is more so in the second, but the "been alone" worked well at the start, some good use of "lights going out"
I rate it better than many bigger budget horrors, who have 10 times the money and churn out bad story/bad acting/bad filming/no jumps....this one got 2 maybe 3 times, might not sound a lot but its very, very rare if I jump in any modern horror film.
The only thing I would change is the interrogation room flashback, should have been kept to video screens, the flashback felt out of place, acting was at its weakest there.