“John Wick” stars Keanu Reeves in a film that doesn’t try to do anything more than be a thoroughly enjoyable revenge movie with an enormous sense of style and visual flair.Reeves plays the title character, a retired hitman who lost his wife due to a terminal illness. She leaves him with a brand-new puppy to keep him company. Before long, a gang of criminals attack John and make the fatal mistake of murdering the pup, and now John is out for revenge.