I could just like the above and be done with it, but I felt the need to expound upon my reasoning. If it's of value to anyone, click on the "thumbs up". If not, no worries. My fingers got exercise.
Up front, I want to specify that this is a personal preference. As with all things, YMMV.
The largest iPad Pro is SO CLOSE to being able to replace my MacBook Pro for the reason I purchased it... music production via Garageband, and Logic Pro X down the road.
I can now connect my bus-powered USB 2.0 Behringer UMC204HD audio interface to my iPad Air via the Lightning to USB3 Camera Adapter (MK0W2AM/A). This means I can record anything through my iPad (vocals, mic'ed up acoustic guitar, direct guitar/bass input, mic'ed up combo amp from my guitar/bass, MIDI keyboard)
So what's holding me back?
Recording is one thing, and the iPad can do this and do this well. Editing/mixing is another matter entirely. The precision in selecting and editing with touch on a small screen vs. trackpad/mouse on a larger screen makes me go to my MacBook Pro all the time (it is the only Mac I have, by the way).
Finger precision on a 2048-by-1536 Retina display (on the iPad Air) is nice, but I oddly find trackpad precision on a 1280x800 non-Retina display works better for me, at least for audio selection/editing. I'm certain it is mostly a screen size issue. On my MBP, when I need more display than that, I can connect a bigger display for greater precision without a loss of latency. AirPlay just doesn't cut it when time matters.
On a 12.9" iPad Pro, editing/mixing would certainly be an improvement over the iPad Air, which is why I say it is close, for me, to being able to replace my laptop for music production purposes. One thing an iPad currently can't do... run Logic Pro X, which is my next step.
I see mixed-use iPad and Mac for me in my future, at least in the near-term.
Having a machine that runs all my old gaming consoles for nostalgia and 8-bit enjoyment doesn't hurt the MacBook Pro's case, either.