Watching this as someone who knew almost nothing about Judy Garland's life was a crash course in the end of her career. The film picks up with a broke, unemployed and homeless Garland in her mid-40s, struggling to keep custody of the children and physically and mentally damaged by years of substance abuse.

Through flashbacks, we see how she was abused by the studios, pressurised to keep her weight down by using amphetamines and be told in no uncertain terms that she is disposable, someone who is only special because of her singing voice.

There isn't much about the film which is special; I was often guessing who people were and the plot is quite thin with highlights few and far between (I really liked the scene where she meets two gay fans, ending up making them a late night snack in their flat).

It's a film dominated by Renée Zellweger's performance, one which is a remarkable transformation and there were times where, if I knew nothing about the film, I would have struggled to name who was playing Judy Garland.

Every time Zellweger takes the microphone and sings, the film comes to life; the interactions between Judy and Mickey less so – I had to look on the Internet to find out some of the people work because I was confused between Mickey Deans and Mickey Rooney and it felt that director Rupert Goold assumes people will watch the film with a good working knowledge of Judy Garland's life. If you are going to watch this, it's probably worth doing a bit of reading beforehand so you aren't pausing it to do some online research.

The film is only good because of Zellweger's performance – a less committed and convincing portrayal of Judy Garland would relegate this to mediocre status.