The Agent Apsley wrote

V.O.S. (2009) (which denotes that it is the original version, but with sub-titles, i.e. not dubbed) was introduced as a film within a film, taken from a play within a play (which is by Carl Lopez), but it is more like Pirandello than anything else, with Brechtian Verfremdungseffekte thrown in for good measure, plus a hint of Woody Allen's Deconstructing Harry.

For the four principal characters do not have - are not shown to have - any existence outside of the film, and though they are stepping in and out of the role as scenes are played out (and envisaged, in discussion, as having taken or to take a different course), it's as though their life is on the set or lot, which makes the experience of watching a lot like that of seeing Nine (2009) or Dogville (2003).

Woody Allen is even mentioned by Clara (Àgata Roca), the pregnant partner of Ander (Andres Herrera) who is seemingly writing the film as it goes, as if it were a linear process that leads up to the scene that we see at the beginning : one audience review that I have seen recently at Cambridge Film Festival critiques an accent as if were less convincing at the beginning of shooting and that that fact is necessarily reflected in where the scene appears within the film.

What does the suggestion that the actors have a life beyond the parts that they play add, when doors that we have been shown into a hospital theatre are later revealed as a mock-up, but then have figures dressed for a procedure emerge from them and appear to be received by the crew as if they are real surgeons or the like? As far as I could see, it merely put a layer of doubt as to whether any of the scenes played out have any status, which is something that Allen has explored, for example, with the use of a chorus (in Mighty Aphrodite (1995), with the alternative realities of Melinda and Melinda (2004), and in Harry or Stardust Memories (1980).

That said, the story of how Ander and Clara become a couple is still an engaging one, because it shows how they have interacted with Vicky and Manu, and it is not as if Allen has just done it all before. Those who are interested can read more in Variety.