Can't grade this very well, because I can't say I liked it. But it is the story that bothered me, not the realization of the film. The acting, directing, atmosphere, music were all good. It's just that after you see a bunch of people doing things you can't truly relate to, the movie ends. It is educational in the way that it shows the horrors of war as seen from home and the way feelings don't need to make any sense at all and still be strong, but that's about it.
The plot covers a period of a few years in which the poet Dylan Thomas is taken under the roof of a former ex-girlfriend. He is married, brings his wife and later the kid, while the ex (Knightley) marries some other guy. But the tension is there, Dylan is a self obsessed jerk and the new husband comes back home from the war with a slight case of PTSD. Add in some pretty temperamental characters and you have your hands full.
Bottom line: you have to be "in the mood" to like this film. The hard part is defining this mood. I don't think I've ever been in it yet. Ever. So it is probably better watched by adults with a grasp on weird complex human behaviour and maybe a curiosity about Dylan Thomas.