An absolutely phenomenal film, somehow managing to be at once engaging, dramatically strong, historically accurate and exceedingly well made. Despite its overall slow pace, it never *feels* slow; there's never a feeling that the film is marking time. Nor does the drama ever feel overbearing; well-measured glimpses of humour are interspersed throughout, adding to both the realism of the film and the humanity of the protagonists.
All in all, I can't praise this film too highly. Just watch it.