I built it, tested it with humbuckers and thought it sounded fine. Just don't imagine you're going to make your Les Paul sound like a Martin. It gives more the flavour of an acoustic than an exact reproduction.
IMO the Boss acoustic simulator sounds better as do several of the simulators in multi-effects I have (RP 100 in particular) but the Woody is way easier to build and does exactly was Mark says it will do.