I always have a faint feeling of danger every time I use screen(1) on #Linux. Because it is meant to be a seamless virtual terminal, there are no visual hints about the keyboard shortcuts required to leave a session for example. Even after pressing Ctrl+a, there's no indication screen is in command input mode, so it always comes as a surprise and a relief to me that the next command actually does what I expected.

It's a sense of dread similar to using vim(1), but at least vim shows the command as it's typed. On the other hand it's always very confusing when I forget to enter input mode and start typing text.

*shivers*