I was an early beta-tester for this plugin - it has worked great from the get-go.
When WordPress cropped the images on it's own, my users would end up with some weird, not-very-nice, poorly cropped pictures on their posts.
With this plugin, images are automatically resized - in their entirety - with any unused portion of the image filled in with a background color, as the images are uploaded. So instead of some poorly positioned crop, the whole picture is used, but with a standard, across the board, size, so all the images appear correctly in each post.
Anyway - if you need this functionality, you'll know what I mean. This plugin has work very well from the get go. Set it and forget it :)