I like 'transgender' as an umbrella term because of its inclusivity; it eliminates the divisions within our community that are created by other labels. I also like to apply the term to myself because it nicely describes the ambiguities between my physical sex, gender expression and gender identity. It's a term that bridges the gaps left by other labels – particularly that chasm that can sometimes appear to exist between the terms crossdresser and transsexual.
There are some people who do not feel the term is appropriate to them. And that's cool, too. But only so long as they don't use that position to narrow the definition of the word and create new exclusions within the community.
Natasha