Never been on a cruise before (myself and wife) and I would NOT enjoy any type of formal dressing up; so, chose this for a beginner.
The embark and disembark went well and if you are fearful of sea sickness...the ship is too big to be rocked by a few waves.
Cabin was clean and perfectly adequate. The Coffee machine was inadequate but I could ignore that.
However, a couple we met on board had terrible problems as their inside cabin 5th level smelled badly of urine and waste. It took them 5 days to be moved... various promises what a negative experience.
Historic Centre (Old Town) of Tallinn is GLORIOUS!