I've had mine for a week now, and have been able to use it alongside my late-2014 rMBP, which has been a solid workhorse. I'm starting to notice very subtle preferences for the 2017 model creeping in - after an hour of typing, for example, going back to the old keyboard feels really, really inefficient and antiquated, and my typing rate is lower than on the new rMBP. I also really enjoy the Touchbar - it hasn't been…
I like the feel of the keyboard, but I found absolutely no way to orient my fingers over the arrow keys. There is no way tell whether I'm hitting the up arrow or the right shift.
As someone who works with text, it's a deal breaker for me.