Returned back home today from a rather epic trip.
2400ish km completed, the car is now mostly run-in. I've broadly followed the Preuningers GT3 run in advice, which is to slowly increase load, try to vary it and avoid multiple cold starts. Basically 4000rpm for the first 500km, 5k rpm for the next 200km etc. etc. I was more circumspect (1) because I'm cautious and (2) because anything over 5000rpm in all gears is well beyond the speed limit.
Now, for the bad:
The front splitter already has plenty of scrapes, entering lodges, entering driveways, all give scraps. So that'll likely just get increasingly scraped over my ownership.
The electric handbrake is unintuitive, you pull to release and push to engage. Odd.
That aside I have no complaints. The car is a rougher ride than a comfortable cruiser, but it handles the long road exceptionally, fuel consumption if you drive miss daisy could probably be as low as 9s, but with relatively good speed I saw more like 11s.
The comparison with the Z4M is appropriate, the car rides and handles noise materially better. Sadly the as fitted dunlops give a lot of tyre noise, I'll be keen to see what a pair of PS4S's does on that front when the time comes. The sound system and ergonomics are all exceptional as well. Neither myself nor my partner felt beat up over the trip, even after back to back 600km+ driving days.
The car is horrendously dirty now. Fortunately as part of the PPF there is a first clean included (partly so they can inspect the curing, sort out any small bubbles whatever). So it'll head back to C&W tomorrow and likely sit till Tues/Wed getting sorted.
Coming back through the tunnel I found the chance to let it rip to around 6500rpm, the sound is incredible. But, the car's capability is so far and above my own it *very* quickly becomes scary! Not in the same way the Z4M did, due to the viscerality, simply because the outright speeds you do with ease are so far divergent from what regular traffic does. Overtaking in 5th means you'll be seeing the far side of 150km/h by the time you're pulling back into lane. And this is with minimal, maybe 40-50% throttle only.
The worst thing by far is the odd electronic handbrake. I'm still getting used to pulling to disengage, so I almost always get that wrong - suspect it'll just take time. But it remains annoying! A pic of our journey is below:

To say it's a magnificent car would be an injustice.
Aside from the refinement and outright power, the grip levels are off the charts compared to my previous car. Whereas the Z4M would become quite squirrely under acceleration on corner exit the GT4 grips so heavily on entry that you simply maintain your speed through sweepers with ease.
The gearshift is marvelous, I'm no senna but there's a great clunk and a proper mechanical feel shifting 2-3-4, the car simply pulls and the down-shift autoblip is a nice gimmick. As compared to the Z4M again it's just more connected feeling. At times the Z4M, particularly 3-4 could feel very rubbery and the throw was much longer (the throw in this car is very, very short).
As I say I'm not a great driver, so for me it's very much about knowing your limits and driving within those. I have plenty to learn on the car before I'm even close to able to really push!