I know I can see the % for each file, but it would be interesting to know how long the entire sync process will take (e.g. how many MB/GB are left, and what the current transfer speed is), from the tray icon, or at least the program status bar.
At the moment I have to look at the list of pending files from the activity tab, select each one to see how big it is, and try to guess the total. Pretty laborious and unprecise, in my opinion.
Take it as a suggestion, if you want.