Buggy but workable
The app requires the plex media server (free download) to be installed on a Mac that essentially should be on all the time. No windows version available.
Setting up everything so it can see your video, music and photos plus remote access on your iPhone/iPad need a person who is familiar and comfortable with media centers and not afraid of searching forums.
The app has lots of potential but still buggy in some areas especially with the iPad (in landscape mode). Performance over 3G even in Tokyo is sluggish. Air video is a better app at streaming videos if that is all you need. Plex opens the door to photos and music.
Overall, the app is buggy but workable and should improve over time. If you cant set up the media server then this app will be totally useless to you.
Moomoobot about
Plex: Stream Movies & TV