Why locals love it?
Locals, if born before 1980, remember what a secret place Viru hotel was in Soviet times. A place where foreign currency was made and microphones where in every room, controlled by KGB. Working in this hotel was a privilege, and it was easier to get a job when you didn't know any other language besides Russian or Estonian.
Why you should visit it
This museum is a must to understand how awesomely the KGB tried to protect Soviet Estonia - meaning totally oppress its citizens. For an interesting and fun history lesson head on to the hotel's top floor and a guide will tell you all the filthy details of what the KGB was doing here.
The only possible way to visit is with an organised tour but beforehand you can also check out the Currency Bar on the second floor of Viru hotel.