I tend to use the keyboard rather than the mouse most of the time, especially for repetitive tasks where it's much faster if I can learn the key combinations for doing something rather than having to point and click my way through a lot of menus.
Sometimes MJ 8.0.336 prevents me from using the keyboard efficiently, though.
The most important problem I've so far is when I want to delete some items from the Playing Now list. I move to the first line, then shift-cursor-down to the last line, and then I press Delete to remove the items. The problem is, the highlight does not end up on the line immediately below the stuff I just removed. Instead it disappears completely. If I press cursor up/down again I end up at the beginning of the list, which may be thousands of lines from where I was, and I have to try to find where I was.
The second problem (less important) is that many menu items and labels lack keyboard accelerators, so in order to use the menus without the mouse I have to navigate through them using the cursor keys. I can go to the plug-in manager by pressing Alt-T M, for example, but there's no corresponding accelerator for Skin Manager. In Media File Properties / Tools, there are accelerators for three of nine items. If I select "Fill properties from filename", there's no Alt-D shortcut for "Directories" or Alt-F for Filename. If I select "Clean File Properties", there are no shortcuts for the four checkboxes.