I played with the idea of switching for quite a while. Having switched my daily driver from Windows maybe 6-9 Months ago I made many mistakes in the meantime.
Good and bad
This may have led to a diminshed experience with ubuntu but all in all, I was very pleased to see that Linux works as a daily driver. Still, I was unhappy with the kind of dumbed down gnome experience.
Problems
There were errors neither I nor people I asked could fix and the snap situation on ubuntu (just the fact that they’re proprietary, nothing else).
Installation
Installing debian (and kde) was easier and harder than I expected. The download mirror I used must not have been great although its very close to my location because it took ages although my internet connections is good.
Apps
Since I switched to Linux, I toned down my app diet a lot. Installing all my apps from ubuntu was as easy as writing a short list and going through discover. Later I added flatpak which gave me a couple apps not available through discover (such as fluffychat). The last two I copied directly as appimages.
Games
I was scared that the „old kernel“ of stable debian would be a problem. As it turns out, everthing works great so far, a lot better than on ubuntu which might or might not be my fault.
Instability
Kde does have some quirks that irritate me a bit like installing timeshift (because I tried network backups which dont work with it and the native backup solution does not seem to accept my sambashare) led to a window I could only close by rebooting.
Boot time
What does feel a bit odd is the boot process. After my bios splash, it shows „welcome to grub“ and then switches to the debian start menu for 3 seconds or so, then shows some terminal stuff and then starts kde splash and then login. This feels a lot longer than ubuntu did. Its probably easy to change in some config but its also something that should be obvious.
Summary
So far I‘m incredibly happy although I ran into initramfs already probably because of timeshift which I threw out again. I might do a manual backup if nothing else works. My games dont freeze or stutter which is nice. All apps I had on ubuntu now work on debian and no snaps at all.
TL;DR: If you feel adventurous, debian and kde are a pretty awesome mix and rid you of the proprietary ubuntu snap store. It also doesnt tell you that you can get security upgrades if you subscribe to ubuntu pro. Works the same if not better.
Ubuntu is a great gateway distro. When I dumped Windows back in the Windows 10 days, Ubuntu made it an easy transition, time elapsed and there were things that didn't work right that I found frustrating. I eventually ended up trying out Fedora and the rest was history. I'm glad you found a good fit for you.
You could try Linux Mint Debian Edition (LMDE) it has timeshift installed in the live iso, useful to restore a system when it's unbootable. Anyway it doesn't come with KDE but Cinnamon or XFCE.
For me Debian or LMDE is good for a home server due to not continuous package update, just major security an important ones.
For a Deskop or laptop in my opinion Fedora KDE or Gnome is the best experience.
Please report back in a few weeks and a few months, and maybe even a year or two down the road.
Generally "I'm really (happy/upset/confused/sad) with it" after only a day isn't really good feedback for people thinking of changing, but it does provide a good baseline to measure against once you're more familiar with it, and getting glimpses into your learning curve might be really helpful for people looking for advice on which OS to go with.
Ubuntu is Debian anyway. Why not installing MX (based on Debian too) with XFCE, it is the best experience I have had.
I come from good old LFS from the 90s and for me, a distro is just a kernel with some GNU utils, a window manager, and a way to get packages (which is about the only diff between "distro")
Unfortunately Debian stable doesn't ship our bugfix releases after the major Debian version gets tagged - KDE Plasma in Debian is currently at 5.27.5, and 5.27.10 was released upstream two months ago.
In other words, you'll be experiencing bugs that have long been fixed... I'd advise to stay away from Debian for KDE Plasma because of that. If you want a Debian based distro with a good KDE Plasma experience, KUbuntu is likely a better choice, even with forced snaps. If you don't need Debian though I'd recommend taking a look at Fedora KDE or Arch (derivatives).
After my bios splash, it shows „welcome to grub“ and then switches to the debian start menu for 3 seconds or so, then shows some terminal stuff and then starts kde splash and then login.
Yeah, the reason for this is that sometimes Debian doesn't enable Plymouth splash screens by default, so you just see the text stuff. It actually annoys me a bit.
Not on my computer at the moment, so I can't remember the exact packages you might need, but if I recall, they should be plymouth-themes and kde-config-plymouth (so that you can choose the splash screen theme in your system settings). You can also find other themes online, but I forgot the name of that website where all the stuff is. Pling? I think it's that.
Anyway, once you have the themes installed, you need to sudo edit /etc/default/grub and append "quiet splash" (with the quotes) to GRUB_CMDLINE_LINUX_DEFAULT= ("quiet" might already be there).
You can also change the value of GRUB_TIMEOUT= in that file to whatever your preference might be for the duration of grub's boot menu, but there might be other things you need to adjust in order to hide it completely and still be able to access it if necessary.
After that, run sudo update-grub so that it's using the new config and choose whichever theme you want in the system settings.
Alternatively, grub-customizer is a GUI app that you can install to do all of the above (which will also update grub when you save your changes). Just don't touch anything that's not relevant. Stick to just the duration of the grub boot menu and add the splash parameter. Ignore boot priority, etc.
It should feel less "slow" to start up once all that's sorted.
(begging forgiveness, I haven't read the comments yet).
Regarding backups - I started with using Ubuntu and its Backup application. This application is a front end for a command line package called Duplicity. One of the things that annoyed me about the backup app was that I couldn't work out how to reschedule the scheduled backup.
Taking control of my own backup setup was the answer. Learn about bash scripting so you can create a short bit of code to handle your backups. Read up a little on duplicity, read up a little on mounting remote file shares, read up a little on setting up an ssh key for encrypting your backup.
This may be an heretical thing to say but I found ChatGPT quite useful in answering these questions (as always with anything you get from an LLM, double check it's answers against reliable sources).
Yeah the boot process is a mess! Debian's noisy GRUB and unsightly boot text is an obvious and unnecessary paint point for a desktop user but very desirable for server installations. You do have some options though!
The great thing about Debian, Linux, and FLOSS is that you can even automate downloading Debian's source package when it gets updated, applying the silent patch, applying Ubuntu's compilation options, compiling the deb, and installing the deb! But yeah why can some package maintainer not provide such as an option in the repository! It's really an annoyance for many and almost makes me feel like I'm not the type of user the Debian community desires. Like, "Wait... what? You like pretty stuff? GTFO!" Maybe its even true? Hopefully you will enjoy using Debian! Its most preferable to Ubuntu in many ways these days!
The splash screen (boot screen instead of text)used to get me. It provided by an application called 'Plymouth'.
You used to need to install it and configure grub, however I think if you go into 'System Settings' and type 'Splash' KDE has an option to install and choose the screen
I tried installing Debian recently as well but didn't get too far into it. I was annoyed at the base configuration* though. I wasn't able to use sudo, so I went to add myself to the sudo group and it told me the command didn't exist... I looked it up and realised that /usr/sbin* wasn't on terminal path. Extremely fixable but something I never ran into on other distros, made me nervous how many other tweaks I may have to do.
I was simultaneously testing Lubuntu and ended up sticking with that after following install instructions for another app kept complaining about bookworm errors. Perhaps the Debian version was too new?..
* Edited a couple of details to make them more accurate.