OK, just a fun topic for a friday: what are the things that annoy you the most in Revit?
Me:
That if you pan/zoom in the middle of a command, and then cancel out of that command with Esc, that Revit will sometimes bounce back to the orginal view you had prior to starting the command. This screws me up all the time, esp. on slower large models that take time to regen.
That Revit still doesn't know how to jive with my dual monitor setup.
That you can't make project families, like walls, export onto specific layers within a DXF/DWG.
The Plant Editor in Accurender.