Warning: there are possible spoilers in my review.
I love the movie. However, throughout the movie Vera didn't have anything to hang on to her current reality, nothing to lose.
It would have been so much more interesting if we know who Nico were as an adult right away and that Vera also had a son in this current reality. It would have made it so much more confusing for her to know whether Nico as a boy were real, a dream, or something Nico as an adult told her, and it would have made it so much more emotional for her to choose which reality to keep: to recover her daughter or keep her son. So the set up is there but somehow the writers didn't use it.
Instead Vera has a very straight forward option: getting her daughter back as any mother would. Who in the world would choose to stay with a relationship you just realized you had over the love and care for your daughter for over 9 years? So the movie is great but dry even though the emotional side is there all along. Unfortunately, the writer decided not to use it, which caused it to not have the strong payback it deserves.
Conclusion: great movie but weak ending.