Diffly is designed to make it easy to browse a Subversion working copy and see all the changes, across all the files. You can filter out files you don't care about (e.g. externals) and sticky-select files for checking in. When it comes time to check in it's easy to review the changes for the files you are working with and assemble a detailed commit message and check-in.
Diffly does not attempt to be a general Subversion GUI but is streamlined to make what it does simple, logical, and fast. It makes a good complement to a more sophisticated but less focused application like SvnX.