There seems to be a fair bit of chatter comparing this to the 12" rMB, so I shall add my 2c to the discussion:
My primary use case for my (2015) 12" rMB is portable work machine for when I travel. I use a Citrix VPN to access my work "desktop" so the rMB had more than enough power. My main bottleneck is spotty hotel wifi or mobile internet, which is of course an unsolveable problem. I initially picked it up for its teensy tiny size ('downgraded' from a Retina MBP) but fell in love with the butterfly keyboard. While on the road the only accessory I use is a mouse, so I picked up a Logitech bluetooth one and have never ever thought in my head - damnit wish I had a proper USB port. I have a Classic Mac Pro at home for every other computing need I could possibly have.
After using it for a while though I found that you could have something 'too small'. It almost felt a little too dinky, especially when actually using it as a 'lap'top, and while going from 13" to 12" didn't seem all at much of a step down in real world use I could tell the difference. Or maybe my eyes are just used to the 13" screen, I dunno. Anyway, I lived with it because well, there wasn't anything else compelling.
Until now that is. I purchased a Space Grey model over the weekend and couldn't be happier*. I am back at 13", have no need for nor interest in the touchbar, lack of connectivity (and apparently gimped processor??) does not faze me in the least, form factor feels 'just right', butterfly v2 is even more awesome than butterfly v1 (though I realize this is subjective), weight isn't that much heavier that it becomes a burden.
* - that is, until another 18 months have passed and Apple release the next generation MacBook / MacBook Pro with some other awesome killer feature, but that's another story..
Happy to answer any 'real world use' questions between the rMB and the new non-touchbar MBP. Don't ask me for benchmarks and the like though, I have zero interest in all that stuff.