I understand the critics, but it depends what you're looking for.

Rating: 7/10 (7 January 2018)

I can fully understand why the critics gave this film poor ratings, as there is a lot to criticise if you are looking to do so. On the flip side, The Greatest Showman can be viewed as entertaining and uplifting if you aren't after perfect writing.
Although the songs are well written, generally their style and delivery are completely wrong for the setting of the film. The majority of the musical numbers come with modern choreography and musical style. Some may like this, but it does detract from the overall "lost in the film" feeling.
The story itself was entertaining, although I am sure doesn't follow the true history of Barnum's life, which again opens itself up to criticism from those who feel it should. I didn't feel this an issue.
Sweeney Todd (2007) is the only musical I can say i really like, and it did much more to use the music to bring the audience into the movie. In the Greatest Showman, it seemed like an unnecessary added extra, done only to attract fans of musicals. There were a few points where I enjoyed it's musical nature (the bar scene where Phillip joins Barnum), but generally could take it or leave it.
Despite all this, I still rate this film fairly highly, as it is entertaining. Anyone who likes modern dance troupes (not me), and that kind of "Britain's got Talent" style entertainment would love this film. Although, most people will be able to get some joy out of it.