It wasn't until I started doing my PhD work where I realized the Overleaf is useful, because the collaborative tools are extremely handy. LaTeX is very popular in the academic world, and Overleaf allows me to easily work on papers with my advisors (who live in a different continent). It's been great.
I do wish they'd add Pandoc support; LaTeX is cool but I find Markdown considerably more pleasant about 95% of the time, so it'd be great if they could let us use that, though I realize this is probably easier said than done.