I bought one in November, and it taken until 2 weeks ago for apple to fix OS bugs before I could even use it.
They screwed up the security, sound hardware, drivers, and midi. So I couldn't use with my DDJ 1000
Even though it's now patched and updated, I can only only ever use it with the internal SSD. Full disclosure, I could see problems like this down the road, so I bought an NVMe and a thunderbolt 3 enclosure and I run it from that. But because of the way that Apple have the security setup, you can't install kernel extensions (kexts) to external drives, only the internal.
So eventually one day the internal SSD will die. . . and I'll have a brick.
I will say this, it does fly like everyone says.
I will stick with it and use the external SSD for everything else, and reboot to the internal drive when I need to DJ. That should help with the longevity.