The free app is arguably even easier to navigate than the IMDb website, with the ability to search for actors, movies or TV shows, as well as some quick and easy shortcuts to popular movies, and lists. You can add shortcuts to the home screen, check through your browsing history and look at photos automatically resized to take advantage of the iPhone's screen.
It has full access to the entire IMDb database, so there's no content missing in the iPhone app version. The only downside of the app is that the ability to show session times based on your location is limited to the US only, which isn't too much of a surprise given that IMDb is actually owned by the US-centric Amazon.
But for free access to the massive IMDb database, this app is impossible to go past.