Ye its fantastic, on really hot days when you feel like you cant breath just jump in and switch the climate control to 16 degrees.. fantastic, deffo worth 695.
RE the fuel thing, I drove all the way back from York with the aircon on and it didnt affect my MPG in the slightest, I think the extra fuel usage is a load of bollox... it might rob you of a bhp or two though.
Its not just the aircon either, when its cold outside you can just set it to 20 degrees or 21 degrees and thats it, the perfect temprature in the cabin, no adjusting the heat all the time or the fans ..
I would deffinatly pay the 695 extra for it.