I bought a Guild GAD 12 last year - very cheaply from a guy who simply couldn't get on with a 12 stringer. He hadn't even got round to putting on the bottom strap button.
I think I've said this somewhere else on this forum - but the build quality on this guitar is top- drawer. It has a good bright sound, with an action that's fine as it is out of the box. I personally don't think it sounds as good as my Martin 12 stringer, and I prefer the action of my 40 odd year Epiphone 12 stringer - but the Guild is young, and I know from experience that the sound will improve.
One thing I have noticed, though. I normally put D'Addario 10's on all of my 12 stringers and I've always been happy with them. When I replaced what I think may have been the factory originals with the D'Addario 10's, the sound wasn't in the same class. The original strings were heavier.