Al Pacino has kept himself so busy over the past decade or so that the occasional gem gets lost in the shuffle — and that’s certainly the case with this charming comedy-drama from the writer and director Dan Fogelman. Pacino plays the title character, a once-exciting singer-songwriter who has morphed into a parody of his former self, playing the hits for easy paychecks to his aging fan base. (There is perhaps a bit of self-awareness to the performance). The very-late delivery of a long-lost letter of admiration from John Lennon, Danny’s idol, prompts a re-evaluation of both his life and his career, resulting in a reunion with his long-estranged son (a soulful Bobby Cannavale) and a flirtation with a kind hotel manager (Annette Bening, sparkling). It’s as narratively predictable as the day is long, but Pacino and the supporting cast (which also includes Jennifer Garner and Christopher Plummer) exude so much genuine warmth and good cheer that you’ll hardly mind.