Vienna is *definitely* worth visiting.  I don't know about from the
standpoint of mechanical music, because when I was there (1991) was
before I became interested in that, but anyone with an interest in
classical music, art & architecture, history, and other cultural things,
can't fail to be fascinated by a visit there.  I had a full week, but it
was not enough time to even touch the surface.  I visited Mozart's,
Beethoven's  and Schubert's houses, the cemetery where those guys and
others are buried.

For architecture, you don't have to go the palaces or museums; it's
*everywhere*.  The whole city is like a giant museum of architecture.
Even the McDonald's restaurant was in a classical 18th century building
(no kidding!).

If you're into doing any kind of research, they have impressive archives
and were very helpful to me.  Virtually everyone speaks fluent English.

The city is compact and easy to get around in on their excellent subway
system, or on foot (best way to see a lot).  Restaurants are *very* good.

Suggestion:  prepare yourself beforehand by studying maps and guidebooks;
you'll get a lot more out of your visit.  Have a great trip!

Larry Lobel