I have made it and it wasn't great. According to my Finnish former boss, it's popular in prisons and military barracks and illegal unless flavoured. Thus, most has some lemon juice added at the end.
One thing I found out after making it was that you need to feed it with sugar over time rather than dumping it all in when you start as I did. This means the yeast has plenty to eat, but isn't overwhelmed and you end ip with a drier, higher alcohol drink.