The Unborn is decent enough for a rental and perhaps a movie-going experience. It was your basic horror flick. They had some neat stuff going on visually, which should be expected since Michael Bay helped produce it. A few genuine scares in an industry that just doesn't produce a genuine scare anymore.
However, like most horror films there are a few items that are unbelieveable. The rich girl getting possessed. Her not knowing her grandmother her entire life and yet she lives in distance. While the demon blows the spell book into shreds the hero grabs one page and declares they have to finish the exorcism...even though they only have just that single page.
All in all the visuals are worth seeing.