Yeah Windows 11 is fine, nothing wrong with it, its a pain having to turn the security stuff on in the BIOS to install it but once it is installed you can turn it off again, you don't need an online MS account, when installing it disconnect the PC from the internet and chose local account only, or you can remove the online account from the PC later.
There are no adverts, i don't know where this idea comes from but its not true.
The start menu has a different layout to the one in win 10 but its still the start menu, you have customisable pinned apps on the front page and if you click on all apps it takes you to what is essentially the win 10 start menu.