This film is about two aimless and out-of-work actors/scriptwriters who live in a dingy flat and drink a lot (as fits Dylan Moran's stage persona). It almost sounds like this could be another Withnail and I, but that's where the similarity ends.
A sequence of tragic events occurs, which is so unlikely that if it were dramatic fiction, it would read as unbelievable and contrived. The punchline of this film seems to be that they ultimately go on to make a major film based on a script that they write about these events. The actors who then play the characters in the "film within the film" complain that the script is nonsense and that the audience won't be able to suspend disbelief.
This attempt to be clever by being self-referential would only work if the film was actually credible on some level. To me, it comes across as an implicit admission that the scriptwriter of the film itself is saying to the audience "I know that this script is badly written and that the humour is contrived, but because I refer to that by way of a clichéd plot-device, this negates any possible criticisms".
As I said in my review title, I wanted to like this film, so I certainly didn't set out to give this film a bad review. I find Dylan Moran very funny, and I really enjoyed the film "The Actors" (with Michael Caine). In fact it's one of my favourite films. I also appreciate David O'Doherty's dead-pan delivery in his stage act. By the same token, I don't think I was expecting too much from this film either. I hadn't heard much hype about it, and I was just keen to see any film with Dylan Moran in it.
In the end, speaking as objectively as anyone can, I think it's just not a good film, caused mainly by a poor script.