Actually I doubt you can sing a long to this. On the other hand I watched it original with subtitles, so maybe if your swedish is good or you watch this a lot of times you can. But I got of to quite the strange topic - a feeling not unlike something you may have while you watch the movie itself. And I only did so, because I heard that the 2018 version would follow this one. Let me tell you something: the 2018 version feels like a seperate movie alltogether, so you don't have to watch this. And you probably will opt out of watching this.
I still haven't touched the surface of this - no pun intended to the sets build here. Always be aware of when this was made (over 60 years ago or more depending when you'll watch this) and the budget it had - it is a TV movie after all. You still may feel this is the best thing ever made, mainly because it feels like a Tarkovsky inspired work of art. I have not read the source this (and the 2018 version) is based on ... but it is quite Science Fiction loaded to say the least.
This is also quite still - not sound wise (singing and all that), but stage wise. So still that I was wondering if the movie was even playing while I watched the beginning. So a long intro, a slow pace .. and singing. Now I am ok with the first two things overall ... but the singing really got under my skin. Again you may feel entirely different. I hope you do and you are entertained by this. If you feel this is boring/annoying in the first 10-20 minutes do not expect this to grab you later on.
Fair warnings and again, every movie experience is up to the eye of the beholder. I could not find much that made this a pleasant viewing for me - and I have to express that otherwise I would not be truthful. A curiosity for sure and a movie that might be out of touch right now (not just because of the black and white cinematography and the "simple" sets), but may become something that people yearn for in the future.