Several early reviews for Barney's Version are in and they're largely positive. Review links are below.
"The impeccably cast confessional, with a pitch-perfect Paul Giamatti leading the way, nimbly traverses the four decades in its lead character's eventful life with considerable exuberance, visual flair and, ultimately, grace."
Screen Daily agrees:
"If it finally wins us round, it’s also thanks to a nuanced performance by Paul Giamatti, who keeps us teetering between sympathy and repulsion for Barney the Montreal Jewish mensch, marital philanderer, foul-mouthed social liability, hard drinker, self-hater, low-grade TV producer and possible murderer, through four decades of his messily authentic life. Dustin Hoffman also puts in one of his tastiest performances in years as Barney’s peppy, irreverent policeman father."
Variety praises Giamatti, but not the film:
"The dizzying comic energy and intellectual vigor of Mordecai Richler's 1997 satire have largely been drained from director Richard J. Lewis' agreeable but inevitably lesser version of "Barney's Version." Absent the novel's wildly entertaining digressions and chronological acrobatics, the strange, decades-spanning tale of Barney Panofsky -- thrice-married Montreal Jew, hack TV producer and suspected killer -- emerges onscreen as a middle-tier marriage drama distinguished by an excellent Paul Giamatti in a familiar curmudgeon role. Acquired by Sony Classics before its Venice and Toronto bows, the Canadian-Italian production faces an uphill battle connecting with smart, literate audiences."