in my opinion the VG99 is excellent but i'll never buy one.
If you've seen the videos than you know what It does, if you havent i'd wonder why you're asking about it. But i've played around with one and all the features it says it has work just like they do in the videos. You can do anything you want with that thing which is for sure.. Whether or not its a real "synth" i dont think is really relevant. It has synth sounds on it that you'll never get out of a Digitech GX series, Line 6 Pod series or even a Boss GT series like of processors. Yeah it does a lot of amp and guitar modelling but it also does weird synth and arpeggiater kind of sounds, detuning by individual strings (id would venture probably more reliable than a transperformer) the only problem is to get the functionality out of you're tied to a midi pickup (Roland GK or others, lots of Godin guitars are coming with them integrated now) which means a 13 pin cable. I use a wireless so that turned me off. Plus you've got the d-Beam which is awesome, i was playing around with it as a whammy bar and its great fun.
Honestly. If i had a bottomless bank account i'd get one. and buy a warmoth with no hardware and just go get a GK3 and hook it up. But I dont. and rathe rthan spend 1300 on the VG99 and an additional 400 bucks on a decent midi controller to use it with,,, and a guitar with a midi pickup (or just a midi pickup) and have to deal with going wired all over again or spending a ridiculous amount on a wireless midi... well you get the picture.
it all depends on what you want.
I found it difficult to play it without the amp models. like it wont give you signal if you turn the amp models off... i dont know i probably just didn't figure it out right away, i only played it for a little bit.
more bang for your buck to get the GT10 which is my plan anyway. its 500 bucks and does a lot of stuff.