In my view, the biggest problem with PocketGuitar is that it takes the guitar metaphor too literally. You fret the strings with one hand and strum/pick with the other, just like a real guitar. But because of the size of the iPhone's screen, you can only access a few frets at a time, and you can't slide up and down the fretboard gracefully. Even if the developers could fix this, I don't think it would make much difference, simply because it's too cumbersome to hold the iPhone in a guitar-playing position.
Since then, we have seen the release of revolutionary new apps, like ( Macworld rated 4.5 out of 5 mice ) and ( Macworld rated 4.5 out of 5 mice ), which are impressive musical instruments in their own right. Where they succeed, and PocketGuitar ultimately fails, is that each starts with a familiar metaphor, but then puts its own multi-touch spin on it, producing an entirely new type of musical instrument. To me, this is what I find most interesting about the iPhone as a development platform.
So, if you're an experienced guitar player just looking for a way to kill some time, then PocketGuitar might be for you. But if you're a beginner, then skip this app (and the accompanying frustration) and put your money towards buying a real guitar. It'll be easier to learn, and far more satisfying.
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