I set up Qubes OS for and with technical, less-technical and non-technical people and I very much disagree. It only works well for those who are prepared and motivated to learn, and even then, it sometimes can be frustrating.

The copy-pasting between VMs, mentioned in a sibling, requires four steps: (1) copying to the source VM's clipboard, (2) copying to the global clipboard, (3) copying to the destination VM's clipboard, and (4) pasting to the destination. The shortcuts become part of your muscle memory after some use, but until they are, that is just one way in which Qubes gets in the way of productivity.

There are a bunch of minor quirks, often specific to the hardware, which the user needs to learn about and find workarounds for. But if they do, Qubes is probably the most seamless way to work with tons of (well-isolated) VMs. For example, SecureDrop [0] is based on Qubes and does seem to work well for journalists for securely receiving and working with documents from anonymous sources.

[0]: https://securedrop.org/