See the Changelog for list of features and fixes.
Public Build 6: Threaded file transfer, stored size settings
The big change this time around, in response to the many problems the client had uploading files on Mac and Linux, is a complete shift of the file-transfer system from relying on Qt's single-threaded event model for handling socket communication to a multi-threaded, one-thread-per-transfer model. This went a long way toward simplifying things, and had the unexpected effect of greatly improving download and upload speeds on all platforms when the bandwidth capacity is there. As usual, and although my own tests yielded very good results, where old problems go away due to a complete redesign, new problems may pop up.
Secondly, several of you have been asking for the client to memorize size settings. This is a necessity especially on Mac and Linux, where the default Qt font is bigger, and the contents of UI containers such as splitters and list columns may have to be resized every session anew. Public Build 6 remembers the size and position of the main window, and all splitter positions and list column sizes (barring any ones I may have overlooked.)
Builds are available on the download page for Windows, Mac and Linux.