What are the advantages and disadvantages of using XHTML?

* All the same advantages of HTML, plus: * Same as HTML, with more rules * Aids in learning proper XML markup and syntax * Forces many cross-browser compatibility issue fixes * Easy to pick up on * All the same disadvantages of XHTML, plus: * Does not fix all cross-browser compatibility issues * Difficult to begin using if writing non-XHTML syntax has become a strong habit