I've been running testing for quite some time. Runs well. Sometimes some smaller hiccups during the freezes. They don't promise you'll get security patches on time (with anything but stable). Otherwise nice rolling distro. I'm occasionally mixing in packages from unstable.
Debian operating system
Debian is a free operating system (OS) for your computer. An operating system is the set of basic programs and utilities that make your computer run. Debian provides more than a pure OS: it comes with over 59000 packages, precompiled software bundled up in a nice format for easy installation on your machine.
I would say testing is okay - I have used the same install on my desktop continuously since early 2022. It's the same as usual - some packages might disappear during transitions and then reappear, like FreeCAD. When that happens, I just use the Flatpak. I think the only major issue I've run into with current testing was some of my systems got borked during the time_t64 transition and I had to chroot in and fix them, but that got sorted out months ago and is probably the only huge issue I can think of.