Went to this place twice so far. Both times were absolutely amazing.
The first time I went with a group of friends (5 people) and did the Hangover. The second time was with my teammates from work and we did the Haunting (9 people).
The puzzles were just the right difficulty (not overly hard but when you solved them as a team you got that big sense of accomplishment to high-five each other). The first time we went a little over time but the owner said it was fine as long as there was no one waiting for the room after, which I thought was very nice of him. He always tells these really interesting stories whenever I've gone.
They also provided us with waterbottles to drink the first time we went which was really nice of them.
If you want advice on which room to choose first, I would do the Hangover room. But, apparently the Haunting room might be changing to a 'Da Vinci Code' room in a couple months (like in July 2015?) so you might want to play that one before it disappears.
I plan on going to the Da Vinci Code room when it comes out, since the owner really hyped it up and probably check out the final room (The First Endeavour) sometime. When I do I'll edit my review with more details!