Complex sentence: The horror press loved the film and got very positive receptions at many festivals around the world and was selected as opening film at Film4's Frightfest 2012 however not surprisingly the UK mainstream press hated it.
Split into simpler sentences: The horror press loved the film and got very positive receptions at many festivals around the world and was selected as opening film at Film4's Frightfest 2012. However, not surprisingly the UK mainstream press hated it.