On most modern pages (single-page applications, usually with a single frame in the middle that scrolls), Fireshot manages to capture the whole page, while the browser's own screenshot tool sometimes fails (captures only the screen I am on, not the whole page).

On some rare pages with a header, Fireshot will repeat the header again and again in the screenshot, sometimes obscuring page content. But by and large, a very useful extension to have.

Have had it since years, before browsers used to have in-built screenshot capability. Still have it due to the above reasons.