I ordered one at start of this month - having been playing a Variax 500 for the last year+
They are just arriving here in the UK and the little time I've had to play (at demos) and listen to the 700 acoustic - I'm looking forward to this new "tool".
If you listen to some of the "demo" Mp3s etc on the Variax user group site it might give you a better idea.
The main advantages are just having one instrument that will give you various emulations including several guitar models including 12 and six, a banjo sound, mandola etc.... Plus instant open tuning (both "standard" and your own) virtual capo (up and down!!), "mic positioning", plus a lot more.
The 500 has as I said, has been great for us and includes electric and acoustic voices and when recorded is great!
Let's face it we're talking a tool and as such it does it's job well (nothing to compare)- but don't swap you D.45 for it.
One thing to remember The Variax 700 Acoustic is Not a semi acoustic guitar and when not plugged into an amp/recording deck will be of no real use - it is an electic modelling guitar based on acoustic guitars and other instruments.