First off, know what to expect going into this movie. It is not a retelling of the book of Acts and Paul's many exploits. It is about him reaching the end of his life and passing the torch to the next generation of Christians, as they all grapple with the difficulty of following God in the midst of a cruel and evil world. Knowing that, I don't think you will be disappointed.
I rated this a 10 because I don't know if any movie has moved me more than this one did. At least, very few have. It's not perfect, but by the end I was sobbing uncontrollably in the theater. Specifically, seeing the suffering of the persecuted Christians, and especially Paul's struggle with lingering guilt over his part in that persecution, culminating with the final scene (which I won't spoil here).
I'll admit that some of the dialogue, especially earlier on in the film, could probably be better, as could the quality of some shots or the sound mixing in a few moments. But the acting is strong across the board, and the production design and costumes look very authentic. Most importantly, the drama is sustained throughout, and there are profound spiritual insights to be gleaned.