I also heard complaints about win11 but is win11 really that bad?
YES!!! It tries to force you to use edge, and pushes you to to open an account and every embedded link goes to both edge and to their £££search engine... And its got all the sual bloatware and so on. Ecores dont need 11. In lots and lots of online comparisons with dozenz of benchmarkes 10 actually performs better than 11 with these 12 series CPUs. There are some rare exceptions where 11 is better. But certainly not worth moving to that crap version of windows. You would MUCH prefer 10 IoT LTSC. I have dual boot here. And cannot stand 11.
1. Does win11 force using online account when installing? Can we bypass it?
You can but it tries every trick to prevent that. But thats similar but not as bad with 10 too. The difference is that 10 doesent permanantly nag you to do it once installed.
2. Is win11 really unstable? Is it too bad or still acceptable as every new product always has some faults?
I have had one or two things that are strangely unstable, but mostly its software compatibility issues that dont work or dont work properly. Most stuff does.
3. Is there any severe defect/bug/fault in win11 that makes win11 useless?
Try it. Thers no oveiding bug, the whole thing will bug you though...
Compared to the version of 10 I use, which is basically like a copy of 7 with no crapware installed its a nightmare of microsoft pushing its stuff on you and change for change sake. You spend weeks getting it kicked into shape and along comes an update that makes it start all over again.