Here's a lot of old fashioned Britishness we love. Repressed emotions hidden behind immaculate manner and only expressed through biting witty comments and classy bitching. But having partially lived in and experienced modern UK (or let's just say London, that is a world of its own) for over a decade now, it's the world that's almost gone... unless for such rare moments brought back by the dying breed as Terence Davies.
In that sense, the whole film is definitely sentimental, nostalgic... and gently bitter (as oppose to bitter sweet). Even the scenes of horror from WW1 are somewhat veiled with distinctively old fashioned verses of Siegfried Sassoon. For some reason most scenes with special effects (the scene where Siegfried dropping his medal being most noteworthy) feel so dated too, as in 90's film or a student project of SiFi.
My biggest issue in enjoying the film was that I gradually lost empathy with Siegfried. He starts off as gentle, smart young man, restrained but with lucid enough self-awareness and noble idealism of a youth. Then he dips in relationships with pretty but frivolous guys, predictably gets hurt by them, and then opts for a more conventional life of marriage and child in the selfish hope that the wife and son may give him the light he craves for. And then he ends up a bitter, distant, irritable and irritating old man, who vents out to his poor wife and suffering son, practically the only people left around, for their failure to become the light he wanted them to be.
Now, it's not entirely his fault alone. The horror of the war that scarred him for life and the intolerant society that kept him from acting upon his true love have a lot to answer for. Even his shallow, egoistic post-war lovers are largely because such bold 'crazy' ones were the only people who could live somewhat openly as gay in the repressive British society.
Nevertheless Siegfried had so many privileges - his uppercrust background, artistic talent, social recognition, and few but supportive friends. Despite of it all, he makes choices against his own truth and heart, and ends up a bitter resentful old man. His last ditch attempt to God wouldn't give him the solace he craves for.
I guess that is actually the message of the film - how giving up one's true heart and truth, whether by one's own will or circumstances, can leave one just a shell of oneself. And what's the worth of a poet when he can't speak his truth?
Overall it left me somewhat unsatisfied after 2 hours of run despite of its many enjoyable and charming virtues. I suspect Terence Davies himself has never quite overcome the pessimistic view he manifested in his early trilogy.
