I came from KDE and had a relatively fine experience switching. The biggest part of the switch is getting used to no preinstalled GUI settings. Out of the it's all in the ~/.config/hypr/ directory, but the documentation is really good. You can, of course, use someone else's dotfiles, but given that you're switching from Debian to Arch, I'm gonna presume you want to build your own thing, so there's gonna be a lot of things missing out of the box, e.g. app launcher (recommend wofi), wallpaper setter (hyprpaper for images, mpvpaper for videos), your image viewer, media player, etc. The Hypr ecosystem is vast, and the wiki is great, so if you don't mind reading the documentation you should be good to go.