Not much, but since I’m being real:
I prefer to use an attached mouse when I’m working at the office. An inexpensive USB optical 3 button mouse with a scroll wheel will do nicely. Please, no 1-button Apple mice. The convenience of a right button for context menus, and scrollwheel for scrolling can’t be beat.
My workarea arrangement has just enough space for a mousepad to the right of the MacBook. I also must have a second screen attached. I don’t like the connections along the right side of the MacBook. Attaching the DVI/VGA connector interferes with my placement of the mousepad and use of a mouse. I actually attach the mouse to the USB port on the left side and bring it around the back to the right side. The ethernet port is on the right side too which also gets in the way. If the connections could have been placed in the back, all cabling would have been hidden and would have allowed for more work space.
That’s basically it. Certainly a lot more to like than not like.