Many people have complained about the new interface in Acrobat X. It’s a problem for veteran users of Acrobat, but I understand that, down the road, it may help new users. Veterans, however, are used to important tools being kept in the same place. And not having the name changed.
In Acrobat X the Typewriter tool is now called “Add or Edit Text Box” and it’s located in the sidebar menu TOOLS >CONTENT > EDIT TEXT & OBJECTS. Read Rick Borstein’s excellent post on this (issued today) where he explains how to add the Typewriter tool to your menu bar.
I hope that this is the last time that Adobe makes changes to the Acrobat interface. Especially seriously disruptive changes like the ones in Acrobat X.