Perhaps paraphrase relevant content from the wiki, Qubes docs and Joanna, so that normal users understand the point of using a Whonix-WS DispVM.
Before we had just a stub. Now, Qubes-Whonix DisposableVMs are fully documented thanks to contributions by the community.
What are DisposableVMs?
Under the Qubes TemplateVM model, any changes made to a TemplateBasedVM's root filesystem are lost upon reboot. This is advantageous for several reasons: it allows centralized (and therefore faster) updates for all applications (most) inside the root filesystem, saves time and disk space.
However, certain directories are designed to persist between reboots in order to store files and settings. These directories are stored in /rw/ and include /home/user as well as additional directories defined by "bind directory" settings.
To ensure that all changes to the filesystem are discarded after a session, Qubes offers DisposableVMs. When a DisposableVM is shutdown, the VM is removed from Qubes and all related VM images are deleted from the host filesystem.
What is a Whonix-Workstation DisposableVM?
As the name suggests, this is a Qubes DisposableVM template based on the Whonix-Workstation. This allows Qubes-Whonix users to create throw-away instances of their Whonix-Workstation.
Importantly, the Whonix-Workstation DisposableVM will inherit the netVM and firewall settings of the ancestor VM by default, meaning the Whonix-Gateway will be safely used.
Why Should I Consider Using a Whonix-Workstation DisposableVM?
- Are quickly generated;
- Are disposed of (deleted) when the user has finished browsing and other activities in a single session; and
- Will not remember any of the user's activities across DisposableVM sessions, unless customized.
The major benefit of this approach is that the Whonix-Workstation DisposableVM can be created in order to host a single application - usually the Tor Browser - without any risk that a compromise of the browser will effect any of your other VMs.
Critically, a Tor Browser exploit will not effect (poison) later instances of the Tor Browser running in a subsequent DisposableVM session, because the DisposableVM is always started in a clean state.
Can I Customize Whonix-Workstation DisposableVMs?
Yes. For advanced users, the instructions include steps to create a customized savefile that will remember specific changes, such as personalized Tor Browser settings. Due to concerns over possible fingerprinting issues, users should carefully read the wiki warnings before proceeding on this course of action.
Can I Easily Add DisposableVM Entries to the Qubes Menu?
Yes. Steps have been included which successfully create entries to the XFCE4 menu in Qubes 3.2.
What Else Should I Know?
Due to a few usability issues affecting anonymity, do not use Whonix-Workstation DisposableVMs until:
- You understand Whonix-WS DispoableVMs are NOT yet amnesic; and
- Have carefully read and understood the available Qubes-Whonix DisposableVM documentation.
Alternatively, you may wish to wait for Qubes 4.0  before you start using Qubes DisposableVMs, due to significant enhancements planned for the later release.