This is literally the biggest waste of time I've ever had in my life! The first day we got the red line, and we had no idea the audio is on an app on your phone, not the bus. The wifi on the bus is sketchy at best so you may or may no get the audio at all, and the app is glitchy so by the time you get it to work you're way past what you were looking at anyway! That's if you know where you are to set the audio off in the first place. The staff said it picks you up automatically and starts - spoiler alert, it doesnt. You have to do it manually and have no idea where you are at any point to set it off.
We figured maybe that was just a bad line so persevered and tried the blue line the following day. I would never have believed it possible, but that was even worse! Apparently the bus went backwards on the map so we went from stop 1 to stop 8 (nobody told us that), then we missed some stops, created new stops that didn't exist at all, and did the stop numbers in such a bonkers order it was absolutely impossible to follow where you were on the audio at any point! Add to this that that there are hardly any buses, and they sell loads of tickets so you can basically never get on and very often wait well over an hour for a bus, and you don't dare "hop off" for fear you'll never actually make it back!
The one star I'll give for the walking tour of the castle however which was outstandingly good, and we had a brilliant tour guide who was really knowledgeable and fun, so that was definitely worth doing. Which was fortunate as that's literally the only bit of knowledge I got from 2 days of the bus.
Do not waste your time and money on this absolutely ridiculous experience, it's not in any way worth it.