I got one. Overall, I'd say its pretty good - comes with a lot of patches, and you can modify patches using 5 parameters (or so - I'm at work right now). I don't know if you know this, but you also need the GK3 pickup, which can be attached with or without modification to the guitar's body. I've heard that its easiest to take it to a tech to get it installed and set up, but I'm a DIY kind of guy so I did it myself - takes a while to get the PU height and GR-20 sensitivity set just right, but not that difficult if you've worked on guitars before/have the confidence to take it on. Overall, the tracking on the unit is pretty good, I haven't had a huge issue with missed notes, though they do occur. Can also be used as a MIDI controller to use with VST's on your computer. I'm happy with it, but I've never used another guitar synth, so I can't compare it to other options.
If you have any specific ?'s I can answer them..
-Peace,
Dan