Has proven so far to be a great learning tool
I have found this program to be a perfect companion to the OReilly "XSLT Cookbook" by Sal Mangano. The ability to test expressions on the fly really helps sink the recipes in that book.
As other reviewers too have noted, however, the program could use some improvement—I have in mind specifically the option to turn off the sound effects, and to open XML source files.
Alptekin Sanli about AquaPath