It's great overall, and fairly convenient, but it has a fair share of bugs and limitations. The Virtualization service crashes with various combinations of Linux kernel version, macOS version, and architecture (ARM/Intel), so making it stable in each setup takes quite a bit of work. Device support is limited (no USB, etc.), and workarounds have other limitations. Rosetta is really buggy.
The popular belief is that Virtualization.framework is inherently faster/lighter than other VMMs like QEMU, but I haven't found evidence to back it up. I spent a day prototyping a custom VMM (with an open-source base) and was able to get dynamic memory allocation working [1], as well as faster file sharing in some cases. There's a lot of other things I could do better (faster, simpler, more reliable) with a custom, tightly-integrated replacement.
But unfortunately, that's not an option. Apple doesn't allow third-party VMMs to set the necessary CPU flags for Rosetta. There are too many users relying on Rosetta for fast x86 emulation for me to ditch it, despite all its bugs.
So yes, I still use Virtualization.framework, but only because I have no choice.
Happy to answer other questions about the framework!