This is certainly NOT a feel-good film, as it deals with the horrors of the Nazis and their crushing of the Warsaw uprising of 1944. After all, there is no way or reason to make this a nice or fun movie to view. It just isn't possible. BUT, we are treated to an intensely realistic and viscerally disturbing film showing the war in all its awfulness. The first portion of the film is set in crumbling buildings and the nobility of the cause is apparent. However, the vast majority of the film is set in the sewers (hence the title "Kanal") and the characters, over time, lose some of their nobility and just ache to survive. The film is intensely claustrophobic and the filth they move about in literally looks like raw sewage--so as the characters fight for life and, in most cases, give up hope, you find yourself being pulled into their world and their terror. A great, though intensely awful film to watch. So, it comes as no surprise that I would not recommend this film to children or people afflicted with claustrophobia.
PS--if the musician seems familiar, it's because Wladyslaw Sheybal (also known as "Vladek Sheybal") is one of the Bond Villains in the movie FROM Russia WITH LOVE.