I used Debian as a student when I had time to endlessly edit config files. What's the state today? Is it possible to just use it to get work done, say, on a Thinkpad?
Yes, you can just get work done with it on ThinkPads (both modern ones, and many older ones).
Debian also offers you a few other desktop environment options, some of which will need more tweaking than the default.
Personally, I ignore all of these, and did my config files tweaking atop Xorg and Xmonad, years ago, and keep using mostly the same setup with each major Debian version since then.
(So far, Debian hasn't forced ads onto my start menu, reverted my explicit opt-outs, spied on me, manipulated me against my interests to suit someone else's business or promotion criteria, etc.)
I find Debian very user-friendly, there shouldn't be much config file tinkering, especially if the machine is well supported by Linux. The situation is probably better than a few years ago, but overall I think that's been the case for some time now.
I'm primarily interested in 1. having all hardware work out of the box, 2. working suspend to disk/RAM, 3. not having to edit `Xorg.conf`, 4. relatively painless upgrades.
Ubuntu gives me all of that and has served me well for 15 years. But their transition to snap forces me to look for something else.
3 hasn't been a thing for a few years now. `Xorg.conf` technically still exists, but the normal display configuration flow doesn't touch it.
4 is better in Debian than it is in Ubuntu, in my opinion. Updates are really painless and well done. But notice that the cycle is different: Ubuntu gives you 6 months release cycles and an LTS every 2 years. Debian gives you a "when it's ready" release cycle with a expected time of 3-4 years, and two rolling releases. That is, "stable" is like a LTS release. If you're running a desktop system, you should probably use "testing", despite the name.
I'm not sure I agree, maybe a better compromise is:
* run stable by default
* if at one point there are too many packages that you find outdated and which have a suitable version in testing, upgrade to testing, pinning the distribution name, so that you're back to (the new) stable once it's promoted
Testing changes a lot right after a release, so I find it better to avoid it during that phase if I don't strictly need it. There are also more upgrades in testing and unstable than in stable, and the less upgrades, the less I need to reboot (or at least close my user session) which is a plus.
You're right. But, to be honest: my solution to that is to run unstable.
One issue with Debian was the lack of support for proprietary firmware in the stock installer from the Debian web site. A lot of people trying Debian and not aware of this ended up stuck with no WiFi support during installation for example. But this has been fixed, the Debian Bookworm stock disk image includes firmware now.