It’s not conceived as a product for end-users, instead it’s the place where contributors are uploading newer packages. Daily. Yes that means that Unstable is a quickly moving target and it’s not for everybody. But you can use it and your computer won’t explode.
1. It contains mainly stable versions of the software
Yes, you read it right. Unstable is not full of development versions of the various software. It happens on some software but then it’s usually a conscious decision of the maintainer who believes that this specific version is already better than the previous one.
The packages in sid are supposed to migrate to testing, the place where the next Debian stable release is prepared. So maintainers are advised to only upload stuff that is of release quality, the rest should be uploaded to experimental instead.
2. It doesn’t break badly every other day
Breakages happen but they are not a big deal usually. It has been long time since I could not reboot my computer after an upgrade or since the graphical interface was no longer working. The kind of breakages that you have is that one software stops working, or triggers an annoying bug, or that a few packages are uninstallable.
In most cases, you can save yourself by downgrading to the version available in Testing. Or by finding a work-around in the bug tracking system. Or by not upgrading because you have apt-listbugs installed and you have been warned about the problem.
3. It’s the basis of other distributions
4. It’s not inherently less secure than Stable or Testing
High impact security vulnerabilities will usually be quickly fixed in Stable and Unstable. The stable upload is done by the security team while the unstable one is made by the maintainer. Testing will usually get the fix through the package uploaded to Unstable, so testing users get security updates with a delay.
For less serious vulnerabilities, it’s entirely possible that stable does not get any update at all. In that case, unstable/testing users are better served since they will get the fix with the next upstream version anyway.
Of course, it happens that maintainers are busy or that something falls through the cracks, but there are other people watching RC bugs who will fix this if the maintainer doesn’t react at all.
5. I use it on my main computer
And many other people do the same. And you can do the same if you meet the criteria below:
- you can work on the command-line (enough to downgrade a problematic package, to edit configuration files, etc.);
- you know how to work with APT and multiple distributions in /etc/apt/sources.list;
- you are able to read/write English so that you can read/file bug reports when needed;
- you have another computer connected to the Internet that you can use to lookup documentation (or the bug tracking system, or the support mailing lists) when your usual computer is off-line for a reason that you don’t understand.
PS: All that said, if you have a working sid installation, do not upgrade it just before an important presentation, or before a trip. It will always break at the most annoying time. Unless you like to live dangerously, of course.