The only thing I miss it has was an automatic save function after taking a screenshot. This would allow for combining (with a script) the output (file) with another tool (such as editing or uploading to a specific service). But that's just a nitpick from my side, because of my personal workflow.

Edit: Well I have another great idea how to improve the screenshot utility! It should bet able to hold Ctrl-key on the keyboard, while clicking multiple elements. Just like selecting files in the file browser. And Shift-key to specify a range of clicked areas. Just for the icing on the cake!