I find this offensive and I imagine many transgender people do, too. The term "transgender" has been around for quite some time so why use an outdated term that has a shaky history? To me, the word transsexual reeks of early sensationalist headlines.
We don't call gay people "homosexuals" anymore. Only wingnuts do that. That's because "homosexual" is a clinical term. So is "transsexual". It is a term invented by doctors to describe a medical phenomenon they were seeing. Why go clinical? Doesn't it make sense to use the term most transgender people prefer?
(Mind you, I'm basing my judgement on comments made by the transgender people I've known. For all I know, there's a huge group who detest the term "transgender". I hope those concerned will chime in in the comments.)
This reminds me of the old days when we tried to convince the New York Times that "gay" wasn't a dirty word. They stuck with the homo terminology for so long! The change was way past its due date when they finally capitulated and went gay.
Transsexual indeed. The word is transgender. At least, I think so.