How hard are these escape rooms advertised?
It really depends. I believe you need to visit some rooms to get known with its structure first. My favorite is https://questfactor.us/national-treasure-shoreline-escape-room So, if you are a real fan and looking for some extra ordinary emotions I strongly recommend that room. Good luck
It really varies place to place. My group consists of 6–8 people who are fairly serious boardgamers and puzzle-solvers. We each have a role we take on in an escape room, from the Organizer, the Big Picture, the Dexterous One, the Timekeeper, etc. We have completed some rooms in record times, and others we have barely escaped with seconds left on the clock.
Most places rate their rooms, and give a percentage rate of how often it gets beat. Start with easier rooms, there are strategies which will make sense to you after a few practice runs that aren’t immediately obvious, but become second nature after a few rooms.