There's no getting around it - this movie is heavy from start to finish - not a moment of comic relief. It is a very sobering film, showing the terrible toll on lives that can occur when evil tyranny is unchecked. It was a fascinating time in history, and an interesting segment of Paul's life to explore -- rather than his 30 years of ministry and 10,000 miles of travel, we get only a focused glimpse into his final days in Nero's prison, with flashbacks to his original time of conversion.
On the upside: This movie is very well done from a production, acting & cinematography aspect. It keeps you engaged; its almost like watching a mystery unfold, due to its intensity. Jim Caviezel (as Luke), Olivier Martinez (as the Roman prefect over the prison), and Joanne Whalley (as Priscilla) were all brilliant in their roles. I mean, really brilliant. (I also loved Joanne in her role of Claudia in A.D.; and Jim Caviezel became one of my favorite actors after "Count of Monte Cristo" and "The Passion". But Olivier was the real surprise - extreme talent.)
On the downside: Most of the movie feels hopeless. What ever happened to the miraculous power and intense encouragement that Paul operated in during all his years of ministry? I feel that the creators of this movie completely underplayed Paul and stripped him of all the elements that made him who he was in the kingdom of God. That was extremely frustrating, since it presented a powerless, hopeless Christianity, other than to be martyred and receive eternal life. Not very appealing. It made me dislike his character more than like it.
In conclusion, the movie is definitely worth seeing for the artistry and story, if you can handle the context, the embellished story line, and a depressing outlook through most of the movie. But if you only like "feel good" movies, you might want to avoid this one.