So as Stokey said we both shared a drive of the new 991.2 , a C2S Cabriolet today, my comparison is against my 991 C2 GTS Coupe which I took delivery of exactly 1 year ago to the day.
First thing to say is it is a very nice package and what follows may seem overly negative but if you were coming from a 997 or earlier, or a 991 without the power kit then this 991.2 would be a good choice but I think it would have to be the 4WD as with the increase in available torque at lower revs, we both thought at times the car felt a bit "on the ragged edge" on the roads we were driving
The first thing I noticed both as a passenger with John and then as the driver was the sound or rather the lack of it, sure there were some nice "pops and bangs" on the overrun, and there is some reasonable exhaust "noise" but it was nothing like the low down "growl" of the GTS and that's compared to the standard exhaust note. Turning on the Sports Exhaust in the GTS and there is no comparison at all, in fact as John said it was difficult to detect much difference with SE on or off in the 991.2.
In "Normal" mode I felt there was some Turbo lag when flooring the accelerator say at 40mph so the way around that was to use Sport Mode all the time but compared to my GTS I didn't feel it was any quicker, yes on paper it may well be (and it's very marginal) but there wasn't anything there that made me feel I must have one of these. Once in Sport Mode then yes it will deliver a lot of instant torque at low revs and the engine will certainly rev all the way to 7000 but when I got back into my GTS for the drive home my car felt just as quick on the proviso that I keep the revs up.
As John said we drove part of the route we used on the Cotswold tour and more recently the afternoon drive at the register Christmas party, so twisty wet roads, not great surfaces but the car did feel a bit skittish with a lot less weight and "feel" to the front end, by comparison I think my 2WD GTS felt much more "planted" on the same stretch of road with a nicer "weightier" and precise feel to the steering.
The standard steel brakes were excellent, I thought they needed less foot pressure than my own GTS to pull up quickly.
I like the new PCM, it's a very crisp display and does look a bit more up to date, it does seem to require more use of the touch screen rather than direct access to menus via buttons like on the current PCM but it's a big improvement which is great because that's what I'm getting on my Macan GTS.[

]
If I was choosing my 911 today, as I was in October 2014, and with the GTS still available then I would do a back to back test drive of both cars and based on my experience today it would be the GTS that I would order.
Having read my post again, it probably seems negative, in reality I think the new 991.2 is a very nice and capable car but although Porsche have tried to get the sound right, the use of turbos has made that very difficult and it just doesn't make the growl with that rising crescendo of exhaust and intake noise as you rev it like the NA GTS engine. As for the car we drove and it's very light steering, feeling skittish, I think the 4WD would be a better bet but I'd have to try it to see.