Being from Edinburgh and suffering/enjoying the International Festival & Fringe for many years this film was always going to be of great interest to me. I did expect it to be dreadful, as so many UK-produced efforts can be, but actually ended-up enjoying large parts of it.
Edinburgh during the festival can be a strange place for the natives - the city is descended upon by hordes of media-types and desperate actors/comedians/whatever. During this time many locals will simply let out their flats at exorbitant rates and go on holiday thereby avoiding the whole rather disagreeable event.
With Festival you can play 'which celeb comedian is that meant to be' as well as 'which pub are they in' and 'where's that again' - being a local helps and you get the same familiar sense of enjoyment as when reading Ian Rankin's Rebus series (also set in Edinburgh.) The acting is good and there are some genuinely funny moments although the dialogue can be quite weak in places.
By miles, the worst element in this film is the music. It's intrusive, adds nothing to the drama and on occasions completely ruins the scene.
All-in-all if you're not from Edinburgh, Festival is hugely entertaining and will probably make you want to come here for next year's ever - if you need somewhere to stay I've got a lovely flat near the Assembly Rooms...