I think only quirky people will really get much out of this film. It's a quirky film, and it's neither totally outrageous nor emotionally engaging.
The premise is pretty simple, but I enjoy watching the way it plays out.
More than a simple humorous jab at Hollywood and star worship... it works as a comment on personality - how you're creating your personality & reality - not very directly, but nonetheless so. That, or maybe I'm just really weird.
Regardless of any philosophical merit, or if you will, lack thereof... I think it succeeds as a light weird comedy.
It's not viscerally hilariously funny, nor is it ultimately profound (though then again, is ANYTHING profound ...if not everything? HA ;P. *ahem). I enjoyed watching it, but it's not something most people can relate to much, while still not weird enough to end up a cult classic.
The film is somewhat similar to Charlie Kaufmann's work - but not as quirky or intellectually brilliant (or puffery. your call.)). If you're interested in Simone, I feel comfortable recommending it - & I'd recommend you also look into "Being John Malcovich" or "Adaptation" if you haven't seen 'em yet!