The killer feature that got me into using it was the shell integration. Your prompt, input and command output are entirely separate entities rather than one single stream of text. It's like using a Jupyter notebook for the terminal.

That was also the thing that destroyed it for me, since navigating between history entries started getting more and more unreliable and sometimes clicking on the input box would randomly resize the entire window or move it between screens. I don't entirely know how they managed that one.