As our GSoC students are approaching quite well, we've already numerous features included in current master, which are worth mentioning. You can try all bellow mentioned features on our demo server.
Grid editing provides really simple way of editing data, by simply clicking on it while browsing table. Just try it on some table.
Performance suggestions are part of completely reworked server status and can give you valuable information how to tune your server. You can see it on demo server.
Another nice addition to server status page is live monitor, which charts basic server information in real time. Again, try it on demo server (you need to press start for now, this will probably go away soon).
Other big, thought not that fancy change is complete support for routines. This includes stored procedures/functions, triggers and events. For example see routines in sakilla database.
Of course there is much more to mention, like improving of AJAX in lot of places, GIS support.
On the other side, we've also recently decided to remove support for Microsoft Excel import and export as used PHPExcel library seems to suffer some licensing issues, which prevented phpMyAdmin from being included in Fedora. You can still use CSV or OpenDocument formats though.