First of all, BIRDSONG is beautifully filmed and acted. Joseph Mawle is especially memorable as Jack Firebrace--who I quote in my title here--a friend and sort of foil character to the protagonist (Stephen Wraysford) played by Eddie Redmayne. Agree: American audiences may find all the British brogues a bit hard to follow without the subtitles.
While there is a palpable storyline and a good surprise at the end, BIRDSONG appeals more to the heart than to the head. It's quite a sad story, of course, but it avoids going too far in the direction of melodrama. It successfully incorporates some really huge themes: Love, forgiveness, loyalty, and others. There is also a great deal of WWI battle footage: BIRDSONG will probably appeal to most war film aficionados. Warning: Some really graphic scenes of carnage at the Somme and various other battles.
Part I shifts every few minutes from Wraysford's illicit 1910 love affair with the wife of a French business partner to his service in the British army between 1916-18. The two time settings are extremely well-synchronized: The directors and producers did a fine job of making the two stories into one. Part II, though it follows the same general pattern, is a little more of a straightforward, solidified story.
I haven't read Sebastian Faulks's original novel, but I've heard nothing but good things about it. It's probably a hard book to cinematize, but Masterpiece Theater did about the best job possible here.
