Even the best acoustic simulators can sound very different to the real thing and it's worth pointing out that the sound that this and other similar units strive to recreate is the crystalline tone of a piezo rather than the warm glow of a mic'd-up vintage Martin.
Sounds
The gain pot acts as a notch for the EQ, ranging from a very metallic tone to a warmer, more rounded sound. For strummed passages the performance is actually quite good, and adding a little treble aids the clarity of fingerpicked pieces.
It'll never replace a genuine acoustic, but for a clean strum, it's worth a look.