Configuration is very unintuitive. In order to change settings, every time you need to select a specific option to write the config, otherwise it will have forgotten your changes next time. Settings aren't organized very well and some settings just aren't editable from the UI, you have to edit the config file directly, in 2025 we should be past needing to manually edit config files.
Once you have gotten the settings down and don't need to change them again, basic navigation like selecting a game to load is fine, but each core has individual settings that it seems that you can only change when the core is loaded, so you have to go through a lot of effort to change the settings for each core...
Slightly off topic, but I can't understand why Parallel Launcher is popular, it's just an extra frontend on top of RetroArch but it hides the RetroArch UI away from you (you need to know the hotkey to access it which it doesn't mention) and it doesn't expose nearly any settings itself so you still need to use the RetroArch UI for most things, then why not just use normal RetroArch directly? I don't really know what N64 emulator to use these days because I've had issues with every single one people suggest.