The newer version has support for multiple IDs ~ doesn't seem to work for multiple Adobe IDs (which would also be helpful), but allows vendor IDs.
It also has support for screen readers (though there have been quite a few forum posts from people who couldn't get it to work for the book itself).
Other than that, I don't know of any extra advantages or features of 2.0 over 1.7.2 ... there may be others.
You can keep ADE1.7.2 and 2.0 on the same machine at the same time, and arrange 1.7.2 to be the default for opening .acsm and .epub files if you like.
I do that, but hardly open 2.0 except to check answers to forum queries.
I can't use 2.0 as my regular, as one of the many bugs is that it doesn't work with Sony eReaders on Overdrive library books, and that is my main reason to use ADE.
For non-DRM books, I use the vastly superior and free Calibre software.
