My biggest complaint is that it's not as easy as it should be to switch the connection to a different device. Still, it's not difficult, either.
The WF-1000XM3s don't have the Bluetooth Multipoint technology that lets you connect the earphones to more than one device at a time. To switch the connection from my smartphone to my laptop, I have to put the earbuds into pairing mode and connect the earbuds manually through my device's settings.
Putting the earbuds into pairing mode isn't difficult. You tap-and-hold the sensors on both earbuds for a few seconds until you hear the pairing prompt. It looks like your plugging your ears with your fingers, which might look a little odd to passers by. But who cares what other people think, right? I'm pairing here!
It's not the worst thing. I'm willing to tolerate this slight complication in exchange for great sound and battery life. If Sony added Multipoint to its headphones, they would be near-perfect.