I think how you view this film might depend on whether you have a bit of empathy or familiarity towards Robbie Williams, or at least like his music. If you don't have that empathy, or familiarity with his tunes/background, then this is more a saga about what the music scene, some years ago (and maybe now?) can do to an individual.
On the other hand, you could also view this as one "oh dear, look at me and how hard I found fame, given my tough background" self indulgent mea culpa.
I have to say, though, I enjoyed it. I think I must be on the empathetic, like the music side of things.
The idea of having a CGI monkey is excellent, if Robbie, or a look alike (maybe it is one) had starred, it would have felt far more self indulgent. As it was, it was watchable, well written and directed.
The film was, however too long (by about 15-20 mins), the middle too repetitive, and the ending too schmalzy. Still, the music is good and, generally not overdone (I hate musicals).
Worth a watch.
