Debian 7 “wheezy” is the latest in the long line of Debian distros. Although a lot of Debian based distros use the testing branch (currently 8 jessie), stable Debians are very much that – stable. This has its advantages and disadvantages, as packages can sometimes get very out of date in the repositories. However, this does not effect security and bug fixes, and that’s what Debian 7.1 release is about.
The extended list is on the announcement blog, but bug fixes have been made on the ALSA mixer, Debian updater and installer, Empathy, LibreOffice, PHP5 and much more. You won’t need to download a new ISO though – all the updates are in the repos, and will be downloaded and installed automatically during a routine update.
If want the new version of Debian though, check out the mirror list for your nearest repository.