Whiteboard UML /= UML 2 ?
Quest in Time: Unwanted Modeling Language: "That UML 2.0 is so geared towards Model Driven Architecture (MDA) that it will loose its focus as, and capability for, general analysis."
Fred also points to Martin Fowler's 2003 post with a similar theme.
But what are the specifics? What is missing or what was added that gets in the way ? I think some great diagrams have been added. And if you are sketching you can ignore the semantics that get in the way.
BTW the Rational's Eclipse based modeling tools referred to in Fred's earlier posting would be one of Rational Software Modeler(RSM) or Rational Software Architect, I assume. And they are both available .