It sounds like quite an unlikely collaboration – rock legend Lou Reed making a record backed the massively successful heavy metal group Metallica. Their new concept album, “Lulu,” is out today in North America, and has left some music fans a bit bemused. A recent review in The Washington Post called it a “multi-headed hydra of unpleasantness.” Ben Sisario, music journalist and reporter for The New York Times, met with “Loutallica” recently, and has a more nuanced view of the new record.