I have a window between projects - foolhardily took the plunge. For a half day's worth of appraisal I'm pleased. For me, at least, it seems to be as stable a first day adoption as one could hope. Resolve seems to work as snappily as ever. FCPX also seems uber responsive. Avid, well, as much as it ever will.
All of the listed programs work on a base level, opening, tabbing through and overwriting a few clips to a timeline or two. I'm sure quirks will reveal themselves shortly. By no means an encompassing list, but my cursory experience with my most important applications. Happy to take requests from those who smartly hold off.
DaVinci Resolve 12.5.2
Avid Media Composer 8.4.0
Final Cut Pro 7
Movie Magic Budgeting 7.5
Movie Magic Scheduling 6
Final Draft 10.0.0
Quickbooks 2015 (Unsupported)
Premiere Pro CS6 (Can't get it to read my R3D's, Quicktimes fine - Premiere CC 2016 untested at the moment)
Working FCPX Plugins:
Neat Video Noise Reduction 4.2
SliceX / TrackX
CoreMelt Lock & Load
iZotope RX4 Color Finale
macOS doesn't seem to allow 1440p displays over HDMI -- mine is capped at 1080p. I know a lot of FCPX users will probably use multiple displays so I figured I'd make sure everybody knew about this one before upgrading.
I'm using a 15" MBP Mid 2014 with an NVIDIA 750m, and there are threads about this in /r/macos and /r/apple so I'm not the only one. SMC and PRAM resets didn't help me but helped some of them.
I see the expected timecode window graphic glitch.
Had to reinstall LUTx.
Did oper Color Finale from main applications folder before running it as suggested in Denver's mail. And it now seems to work fine.
One other weird thing: I run FCPX on a 2012 Retina MacBook Pro with a second monitor. I have the viewer on the MacBook Pro Retina display and everything else on the second monitor. But everytime I open FCPX now they've flipped so viewer is on second display. Slightly annoying, but can't decide if it's annoying enough to go back.
Logic Pro X re-scanned all the Audio Units (FCPX didn't) but seems to run fine.
I used the Ultra MiniMonitor today and it seemed to be working. It did quit FCPX on me once (I could tell by the plugin alert on quit) To be honest I've found the MiniMonitor caused issues before Sierra - causing FCPX to quit or freeze. Tried reinstalling and didn't make much difference.
FCPX is crashing on me relatively frequently (about once per hour) with different process problems each time - although the crashing is not enough to be annoying (& no where nearly as often as the first few months with El Cap!), hopefully they'll sort it out soon.