There has been a lot of chatter about this new Clint Eastwood movie, especially given it is currently smashing box-office records in the US. Some think it's patriotic jingoism, unhelpfully glorifying American firepower in the fight against Middle Eastern terror. Others – particularly the conservative media – are holding it out as a portrait of a hero. Actually, it's neither, nor is it a particularly great film. It just seems to have hit a nerve in the US, where the expensive and deadly eight-year war in Iraq fizzled away into unsatisfying disapproval.

The film is really a biopic of Chris Kyle, a Texan rodeo rider who became a Navy SEAL sniper, credited with 160 kills while on duty in Iraq. When Kyle was discharged from service in 2009, he wrote a book about his exploits, American Sniper, much of which is the source of Jason Hall's screenplay. With Bradley Cooper playing Kyle and Sienna Miller his wife, Taya, Eastwood opens the story with a young Kyle picking up some traditional values about guns and the nature of manhood from his father. From there it's a quick path to serving his country once terrorists attack US embassies in 1988.

But most of the story centres on Kyle in action over four tours of Iraq and his relationship with Taya. As his reputation as a sniper grows, he becomes known as "Legend" to US troops and "The Devil of Ramadi" to Iraqi insurgents. Back home, he's just absent, even when he's there. To provide appropriate Iraqi antagonists, Hall creates an enforcer named "The Butcher" (Mido Hamada) and an opposing sniper named Mustapha (Sammy Sheik). As the conflict progresses, a huge bounty is placed on Kyle's head and Mustapha becomes the man most likely to claim the prize.

Eastwood plays a delicate and not altogether successful balancing act, trying to portray Kyle as both a man who cannot but be affected by his job (his first kill is a woman and her young son), and a zealous patriot who believes in his country and its role as protector. Complicating matters greatly for Hall and Eastwood (spoiler alert, if you don't know the truth about Kyle) was his death in 2013, just as the screenplay was being completed. In an interview, Hall admitted it caused a great deal of rewriting, the pressure now to memorialise Kyle as father and hero. It certainly provides the film with a strikingly tacked-on ending, undermining what would have been a powerful tale about the individual psychology of war, in the vein of the far superior The Hurt Locker. The action sequences are excellent, the plastic baby is dreadful (you'll see it when it comes) and Cooper does a fine job in his most serious role to date. It might get you talking, but it's not one of  Eastwood's finest.