There have been a lot of apps recently that have come out trying to turn your iPhone into a musical intrument. Several of them have been succesful at holding the attention of the iPhone audience, but every now and then there are a few that just confuse you. Fret Guitar is one of them.
After reading through the information on iTunes three times to make sure that it's being used correctly, the app still isn't that great. You're presented with 5 fret icons that are way too oversized on a background that doesn't look that great either. From there, you hold down and let go on any or all of these ?frets? to make a strumming noise.
The app isn't meant to play all the strings of a guitar, but it really lets you down with the fact that there isn't really much you can do and the styling leaves something to be desired. For being able to strum 5 frets at once, the app definitely does what it has set out to do, but it doesn't add anything to the iPhone that you can't do in something like Chord Play.
If you're looking to just strum the same sounding fret over and over again on your iPhone, check out Fret Guitar. That's what it was built to do and that's what it does best. But for everyone else, avoid this app, it will just frustrate you.