I'm not going to remotely pretend that I know anything more than the building of an arc. So I can't touch on how accurate it was or whatever. As a stand alone movie based on Noah's building of the arc, I really liked this movie. It was very powerful in its portrayal of belief and spiritual faith. The family dynamics shown through their dealings with those things was very well acted/directed. The effects were phenomenal. The kids all put in great performances and Russell Crowe was great.
Again - not sure how accurate it all was but I would definitely recommend this movie. I thought it was a well put together "epic" and absolutely worth the time/money.