Production values aside, how would you compare it to the "Jesus Film" done by the Genesis Project back in the 70s with Brian Deacon as Jesus? That was a literal telling of the Gospel of Luke. I can imagine the acting is better in "Gospel of John" (Hey, we are talking about Christopher "Captain von Trapp"/"General Chang" Plummer after all).
What worries me is that "Gospel of John" might come off like the overly Hollywood-ized "Jesus of Nazareth", or worse yet the 50s film "King of Kings". I can take underacting. Ham-fisted, soap-opera style overacting is worse.