I've been busy creating some use-cases in Visio 2007 for an upcoming project and from what I can gather either Microsoft has not implemented the current UML 2.0 standard and stuck with an older version, or it decided what parts of the specification to implement.
Either way it's a little annoying, I'm having to spend extra time working out what was the equivalent diagram or notation in UML 1.2 was in order to draw it in Visio.
An example of this would be where you link two Use-Cases with the «include» relationship. This doesn't seem to exist in Visio, so it looks like you have to make do with the «uses» stereotype instead, which was replaced in the current standard.
A few other Visio bug-bears would be the sparse Use-Case documentation interface. It doesn't allow rich text, so adding more than a few lines of text could become very hard to read. Microsoft also seem to leave it up to the modeller to format their own use-case specification; but with such a poor interface I can't see how you could use table-orientated steps to make a sequence of events more readable.
Surely allowing attachments (in the form of Microsoft Word) to be added would make more sense?