I find it pretty useful. Especially for a free program. I'm running an older version - the latest appears to no longer feature built-in FTP, so no upgrading for me.
I can just right click a file, pick a server directory from a drop-down list, and upload.
Find & Replace not only works on open documents but also all files in a chosen directory - handy when you rename a file and have to update any and all links to it.
It can validate your HTML online via WC3 Markup Validation Service.
You can save code snippets, create projects w/ document dependencies, spell check, bookmark lines, preview a webpage in any browser you've listed. Also you have syntax highlighting, and line numbers if you wish.
Every now and then I think there must be something better out there, so I look around, but end up sticking with CoffeeCup.