Well, it depends on how you use it. Whether its for the guitar modelling or just for effects.
For me, I bought the pedal because my acoustic doesn't have a onboard EQ and volume control. So the pedal sort of became a volume and EQ pedal where I can mute my guitar and do some sound adjustments, Not to mention that it works great in providing reverb. But I think that's all I'll use it for.
In terms of sound, its pretty decent, I think they did a decent job of replicating the clear balanced tone of the Martin models(nothing beats the real thing of course =D). The Gibson models listed are lacking in character. If you can lay your hands on say a real J-45 which is listed one of the models in the pedal, you'll know what I mean. Somehow it doesn't sound as authentic/real enough as compared to the Martin models.
Hope it helps. =D