We played on Midnight mode (both horror and puzzles enabled), which I would highly recommend if you're an enthusiast who wants the full experience. Newer players might want to opt for the less stressful Day version (puzzles only), while haunt fans might appreciate the simpler Night version (horror with very simple puzzles).
This was the only game (out of ~20) on our Athens tour where I had a moment (early on, shortly after we had made our way into the sanatorium and had done a tiny bit of exploration) of "Oh God, this is terrifying, get me out". I'm glad I stuck with it, though - this is definitely type 2 fun.
The set is fantastic - large, atmospheric, and spooky. That's before the monsters and fog arrive to kick things up to the next level. The intense fog also means the GMs can't necessarily visually monitor players - there's an alternate means to contact them that becomes available pretty early on, but players have to be proactive.
The game was extremely tense, which of course made it harder to focus on and solve puzzles. Even more so than many Athens games, they really like their fog machines - there were times I could barely see my hands. I kind of wish I had brought a mask, because I don't know how healthy the fog is to breathe.
I should note some safety problems. The timeout room (where you get put if you're caught by a monster) is somewhat cramped and physically locked from the outside; if a fire happened, it would be bad. At one point in the game, one of my teammates was fleeing from a monster and injured himself by running into a door (it was very foggy and he thought he was further down the hallway than he actually was) - nothing major, just a small cut above his eye, but he did have to call the GM and get taken out of the game to get patched up.
We played in English with no problems.
Particularly interesting or different
Yes
Actors were a big addition to the game, it would have been much less tense without them.
Physically active
Somewhat
Players have to avoid monsters, which involves hiding